My ubuntu (version 10.10 I think) is stuck in loop at the login screen. Looks like it could be a resolution issue. - I have an nvidia graphics card (gs 8400). I previously had it connected to a 19" monitor however disconnected mid session and since then the issue has persisted. I tried uninstalling the gdm package and reinstalling and running an apt-get update however the login loop still there.

Is there another way I can reset the resolution settings to fix this looping issue?

I can get into the desktop by going through the rescue mode and using startx but its not a solution.