login screen problem

[mj360]

i just updated to 12.04 but once it goes to the login screen the monitor says unsupported video signal but i can hear the ubuntu sound so i login without seeing the screen but once i login everythings fine it's just do this at the login screen i don't understand why it's doing this. everyone know why this happening ?

[mj360]

i just updated to 12.04 but once it goes to the login screen the monitor says unsupported video signal but i can hear the ubuntu sound so i login without seeing the screen but once i login everythings fine it's just do this at the login screen i don't understand why it's doing this. everyone know why this happening ?

i'm i the only one who having this problem ?

[anejo]

It would seem so mate... but lets see what we can do anyway to get you to see the greeter screen.
So when you power up your machine...
you get a blank screen...
nothing visual only an auditory clue that Ubuntu is actually doing something?
Is that it?
(And then you login and then you see the desktop)

[anejo]

Also before you login...
If you were to press Ctrl+Alt+F1
does that take you to a login prompt that you can see?

[mj360]

yes that's right.

[mj360]

yes it show ubuntu login in all black when i do ctrl alt f1

[NikTh]

yes it show ubuntu login in all black when i do ctrl alt f1

Hi ,
try to login from there , then do

sudo apt-get -f install 
sudo dpkg --configure -a 
sudo apt-get update ; sudo apt-get dist-upgrade

When commands finish , reboot and see if works.
Thanks .

[mj360]

it didn't work. but i forgot to say, it works when i hook the pc up through hdmi but it don't work with vga.

[NikTh]

it didn't work. but i forgot to say, it works when i hook the pc up through hdmi but it don't work with vga.

Except for VGA(hardware) problem ,
maybe vga's graphics are to low to run with Ubuntu ? I don't really know ... i am not sure.
What is your card ?
Give the output of

lspci -nnk | grep -iA2 vga

Thanks

[anejo]

IF NikTH's solutions are working for you great!
If not, again in that terminal--Ctrl+Alt+F1--what you should try is first get 'gdm' installed

sudo apt-get install gdm

The above command assumes that you have access to the Internet of course.
If not, then do so after you have login successfully.
Remember we are trying to get a greeter-login screen visible for you...
Assuming then that you have gdm installed... at the prompt

sudo dpkg-reconfigure gdm
sudo reboot

The first time you do this--because the lightdm is not showing--select gdm and then reboot.
The gdm version of a login screen should be presented... and you should be good to go!