Login screen won't accept my password

I recently upgraded to 12.04 from 11.10 and since upgrading have been unable to log in to my user profile. The upgrade went okay and I can login to a guest session fine but whenever I try to login to my profile, after entering my password, I just return to the login screen. I've changed my password in Root (passwd <username>) and can log in to tty1 with no issues, it's just in GUI I'm having problems.

I'm using a HP dv7 laptop, 32-bit Ubuntu install, Intel® Core™2 Duo CPU P7350 @ 2.00GHz × 2, Nvidia graphics.

Any help would be appreciated.

Try these solutions:

From your cli remove the .Xauthority file. Some people have reported that they also needed to remove the .xsession-errors files.

sudo rm .Xauthority
sudo rm .xsession-errors*

Finally some people have reported that ownership and permissions on their home folders were set incorrect. Not sure if this will help but it's worth checking:

ls -l /home

you may have to give ownership back to your account using chown

sudo chown -R username:group /home/username