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newbuntuxx
May 4th, 2010, 03:49 AM
Hello All,

I just upgraded from 9.10 to 10.4. I am having the following problem:

When I attempt to switch from the user that I am currently logged into, to another user who is also logged in, I get a black screen.

To elaborate, here is the exact sequence of events:


- Boot ubuntu and login to user A
- Then Click on power menu (top right corner) and select: Switch from A
- I get the login screen
- I select user B and enter my password
- I hit ok
- I am able to login successfully to user B
- Now, I Click on power menu (top right corner) and select: Switch from B
- I select user A from the login screen and enter my credentials, then hit OK
- I get a black screen

Now this where I get stuck! The only key combination that works is: Ctrl + alt + F8. This gets me back to a login screen.

Now I obviously can not login to a user who is already logged in because I'll just end up getting a black screen. At this point, the only thing that I can do is login to a user who is not already logged in, assume root privileges and logout all users who are logged in using the command:


skill -KILL -u user

If, however, all available users are already logged in, then I am left with two options:
- rebooting or
- switching to a shell (ctrl + alt + f1), and restarting the xserver

I did try to change my session (at the login screen) to gnome-failsafe, xterm, even kde, but still I get the black screen.


Hopefully this is more coherent!

newbuntuxx
May 4th, 2010, 03:58 AM
SEE Opening post

editted

newbuntuxx
May 4th, 2010, 04:08 AM
SEE Opening post
edited

Pilo
May 4th, 2010, 04:17 AM
If I switch from user A to user B and user B is not logged in, then I don't get the black screen issue. However, If I try to switch to a user who is already logged in, I get the black screen issue.
I have precisely the same issue.

Pilo
May 4th, 2010, 04:23 AM
Looks like iomtalach and WolverineFan are having a similar issue over in http://ubuntuforums.org/showthread.php?t=1467619

I'm currently running an nVidia MCP78S [GeForce 8200] with the default open source drivers on a fresh install of Lucid with dual monitors.

I believe the problem (for me at least) is the one reported here: https://bugs.launchpad.net/ubuntu/+source/indicator-session/+bug/549632
Which appears to share a root cause with: https://bugs.launchpad.net/ubuntu/+source/gnome-screensaver/+bug/555870
https://bugs.launchpad.net/xserver-xorg-driver-ati/+bug/546578
These all essentially seem to deal with the gamma values not being reset properly after a fade out.

The suggested work-around of hitting alt-f2 and typing

xgamma -gamma 1.0
Works partially for me, it restores one of my monitors but not the other (which happens to be the one with my gnome panels unfortunately).

WolverineFan
May 4th, 2010, 05:21 AM
I filed a bug report. Feel free to chime in with your individual details.

https://bugs.launchpad.net/ubuntu/+source/fast-user-switch-applet/+bug/574909

WolverineFan
May 4th, 2010, 05:28 AM
The suggested work-around of hitting alt-f2 and typing

xgamma -gamma 1.0
Works partially for me, it restores one of my monitors but not the other (which happens to be the one with my gnome panels unfortunately).

You can specify a display to xgamma:


xgamma -display 0.0 -gamma 1.0

xgamma -display 1.0 -gamma 1.0

(My X is a bit rusty, I think that's the right syntax).

I only have one display so I can't test the -display parameter, but I can report that xgamma -gamma 1.0 works for me too. Seems like an easy enough fix hopefully! It would be most excellent if this worked reliably!

newbuntuxx
May 4th, 2010, 07:37 PM
Well, this is what I tried so far:
- Removed the password from all users
tested: still get black screen
- reinstalled gdm
- tested: same thing

In fact, now when I get the black screen, I can't even use any key combination at all! I must reboot to get anywhere.

OwnSurname
May 8th, 2010, 11:24 AM
Same problem here, black screen to nowhere. Sorry guys, I have to write this down clearly: this puzzle me the most, they want to bring Ubuntu to the "normal" user, and then (s)he can't even switch in between two users. Is it *so* difficult to make a small program to switch to another user that work?

maxpoweron
May 10th, 2010, 01:22 PM
I have the same problem on my two PCs; a Dell Dimension 8200 and a Sager NP8690 notebook. I noticed the problem after I installed the Nvidia drivers for each PC.

BFG
May 11th, 2010, 05:06 PM
I have the same, but slightly worse.

ATI card on 64 bit, with and without restricted drivers, with and without special effects - makes no difference. When I get the black screen, the system locks up completely. Not even alt+sysrq+o works.

It's fine on a liveUSB, but I added a dual-boot to try lucid out and these lockups are giving the HDD hell. I have to power off to get out of it and twice I've had "boot disk not found" afterwards. I can get back, but it's really worrying.

Experimenting further, if I don;t user switch, but try Ctrl+Alt+f2, that's fine, but going back to X with Ctrl+Alt+F7 gives me a lockup again, but this time it's purple. Purple screen of death?? :confused:

!nkubus
May 12th, 2010, 09:10 PM
I ave the same issue, I must admin that my GF is frustrated every time it happens. she now wants to buy a MAC lol yiiikes ....

Thorndog
May 13th, 2010, 02:58 AM
Desktop with quad 6600 64 bit etc
Exactly the same issue. Black screen of death. My wife is not too pleased because I can't let her use my user and clog up my browser history, mess up cookies etc with ebay and Paypal etc.
This REALLY needs to be a priority bug fix because (hard, power off)reboots are NOT what I want to be doing every day but neither can we all share our desktop with the family or coworkers or whatever. I really don't want to back up to 9.10 either and waste a day no doubt in the process.
Somebody fix this pleeeeasse.

BFG
May 14th, 2010, 08:11 AM
Desktop with quad 6600 64 bit etc

I forgot to mention above. I have Quad Q9550 with 64 bit. Maybe this is significant. Video Card is a Sapphire 512Mb Radeon HD 4670,

Thorndog
May 15th, 2010, 02:02 AM
I forgot to mention above. I have Quad Q9550 with 64 bit. Maybe this is significant. Video Card is a Sapphire 512Mb Radeon HD 4670,
Different video. I have on board Intel chipset, I think it's nvidia. MM I guess I could check but I don't remember how. Still, if it's only 64 bit users....
I also had a problem withrunning Wesnoth, a game and on a forum there it was mentioned that a non response problem to mouse clicks there was cause by the latest libsdl version. Great. Maybe I jumped for Lucid too soon...

leodamasio
May 16th, 2010, 09:41 PM
Hi,
It's not a 64bit only problem. I have the same issue (black screen when switch users) in a 32 bit box.
Regards

emigrant
May 19th, 2010, 07:28 PM
Its really sad to have this problem in the nicely build lucid.
hope some one soon fixes this.

Ubunting biochemist
May 21st, 2010, 09:56 PM
I am also having this problem on a 32-bit box with an ATI video card. Upgrade from Jaunty to Karmic was no problem. My wife is also none to pleased. I would love to see this fixed!! Thanks.

kleo skywalker
May 23rd, 2010, 11:40 AM
Hi all,

I have the exact same problem with a clean install of 10.4 on a 32-bit machine. I haven't tried the key combinations mentioned in this thread, so I've had to press the power button and turn off every time.

Does anyone have a solution to this?

Thanks.

dino99
May 23rd, 2010, 11:47 AM
Hi all,

I have the exact same problem with a clean install of 10.4 on a 32-bit machine. I haven't tried the key combinations mentioned in this thread, so I've had to press the power button and turn off every time.

Does anyone have a solution to this?

Thanks.

can try:
- remove .gnome
- metacity --replace
- add this ppa: https://launchpad.net/~ubuntu-x-swat/+archive/x-updates

emigrant
May 24th, 2010, 07:18 AM
dino u sure about that?
did u test and succeeded?

hillsimon
May 27th, 2010, 12:15 AM
Hi,

I've tried to restart this bug report:
https://bugs.launchpad.net/ubuntu/+source/fglrx-installer/+bug/290704

Please click that you are affected by it (at the time of writing this there's a total of 27 affected users).

Simon.

emigrant
May 27th, 2010, 06:42 PM
any kde users have this problem?

hillsimon
May 28th, 2010, 10:23 PM
If you're experiencing this problem and have a NVIDIA graphics card, then I've reported the bug
Please visit and click on the green link to report the bug affects you.
https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-173/+bug/587069
Thanks,
Simon.

OldSlacker
May 28th, 2010, 10:27 PM
Same scanario... black screen after switching users, 32-bit system, nvidia legacy g-force, total freeze with no ctrl-alt options, must power down. For what it's worth Linux Mint 9 has the same issue. Have been running Ubuntu since Hoary Hedgehog, currently on Karmic. First time for this problem. Will not move up to Lucid until this is fixed.

djxcon
May 28th, 2010, 11:44 PM
I believe this was a bug in gnome-screensaver but could be wrong. A patch to gnome-screensaver came out today in the repos with a description that addresses this issue in part. I have downloaded the patch but haven't tested.

OldSlacker
May 29th, 2010, 12:46 AM
I found that one on Google, and tried it... completely removed gnome-screensaver... had no effect whatsoever. :confused:

hillsimon
May 29th, 2010, 03:45 PM
Please add yourself to: https://bugs.launchpad.net/ubuntu/+s...73/+bug/587069 (https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-173/+bug/587069)

OldSlacker
May 30th, 2010, 01:40 PM
Please add yourself to: https://bugs.launchpad.net/ubuntu/+s...73/+bug/587069 (https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-173/+bug/587069)

I went to that page, but don't understand what I am supposed to do on it.

On other matters, I can now fully understand why Debian Squeeze is still in "testing". It appears that Ubuntu Lucid should have followed that example. Ubuntu has done a lot for Linux, and that has moved them to the top in popularity, but I believe if the recklessness shown in the past couple releases continues they will lose that place.

hillsimon
May 31st, 2010, 09:59 PM
I went to that page, but don't understand what I am supposed to do on it.

https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-173/+bug/587069

You have to register/login to launchpad (top right).
Then you are able to click on a link on top left saying how many people the bug affects and add yourself to the list.
The more people that do this, the more likely it will be fixed.

salemoh
September 27th, 2010, 07:03 AM
I'm getting a black screen when switching users on Lucid installed on Virtual Box. Did this get resolved?

Thorndog
September 27th, 2010, 06:05 PM
I don't have the problem any more and honestly don't rmemeber when that happened. I have since changed motherboard and done a fresh install. I have switches off screensaver completely since I had problems with that and I think that might have been it. Sorry I can't help more.

WolverineFan
September 27th, 2010, 06:53 PM
I'm getting a black screen when switching users on Lucid installed on Virtual Box. Did this get resolved?

Yes, this was resolved with a patch to the screensaver code I believe. Long before 10.04.1. Pretty sure it had something to do with the fade-to-black stuff.

If you've installed all the latest updates, you have a different issue.

hillsimon
September 27th, 2010, 09:46 PM
Hi,

The problem still persists exists but seems to be related to the particular video driver.

See this one for NVIDIA:
https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-173/+bug/587069?comments=all

Simon

SentientFluid
October 13th, 2010, 04:13 AM
I had the same issue with a fresh install of 10.04 when using the 173 nvidia drivers. Here's what fixed it on my system:

cd /tmp
wget http://mirrors.kernel.org/ubuntu/pool/restricted/n/nvidia-graphics-drivers-173/nvidia-173-kernel-source_173.14.28-0ubuntu1_i386.deb
wget http://mirrors.kernel.org/ubuntu/pool/restricted/n/nvidia-graphics-drivers-173/nvidia-173_173.14.28-0ubuntu1_i386.deb
wget http://mirrors.kernel.org/ubuntu/pool/main/n/nvidia-graphics-drivers-173/nvidia-173-modaliases_173.14.28-0ubuntu1_i386.deb
dpkg -i nvidia*deb


That will download and then install the nvidia 173 drivers used with 10.10 which do not have this bug.

Of course another option might be to upgrade to 10.10.

hillsimon
October 20th, 2010, 10:49 PM
Extremely grateful to you.
Followed your instructions, haven't had any black screens since.
Thanks.