This morning when I booted my 12.04LTS desktop it would not let me log in.
What happens is when I get to the screen to select user name and enter password, after entering the correct password it just blanks the screen and then brings you back to the log in screen again.
If you type in the wrong password it gives you the error message, so I know I am entering the correct password when I do.
I also have a "guest" account that has no password required, and when I tried to use that account it just loops back to the log in screen again.
I tried selecting different versions of the kernel from grub, both regular and recovery versions and that makes no difference.
Since the last Live disk I have is 10.10 it doesn't seem to play nicely with my DVD drive, so I couldn't open a Live session of Ubuntu.
So I went and bought a new HDD (and a 8-gig usb drive) then swapped out the misbehaving HDD for the new one and installed 10.10 on the new HDD (which is how I got to here).
Does anyone recognise this problem? I searched the forum titles for the same issue, and there seem to be a few similar, but they are usually for much older versions of Ubuntu.
I was thinking that my best bet would to be to make a Bootable USB drive for 12.04 and then swap the old HDD back in and see if I can fix things that way.
If it would help diagnose the problem I could also pop the misbehaving HDD in an external cradle before reinstalling.
My PC is a AMD Phenom II X6 1055 with 8G of ram and a AMD/ATI radeon 5850. No other peripherals other than the DVD drive.
I wasn't downloading or updating anything when I shut down.