If you have logged into our UNIX machines before they were all updated to Trusty, you may need to remove your old config files for the windows manager you are using. You can use Ctrl+Alt+F1 (Ctrl+Alt+F7 or F8) will get you back to the graphical login screen) to get to a virtual console and the dotfiles/directories in question are:
- gnome - .gnome2, .gnome2_private, .gconf, and .gconfd
- kde - .kde and .kderc
- xfce - .config, .gconf, and .gconfd