Here's an idea for testing.
Create a new user. If you can't start the GUI tools, you may have to do it from the command line with the adduser and passwd commands. Depending on how adduser works in Mint, you may have to manually create the /home/ for the new user.
Log out and log in as new user. If the desktop works for new user, it's something in the hidden (dot) config files for your desktop environment in your user's home directory. Since you didn't mention which DE you are using, I can't suggest which files to look at, but a little Googling should tell you.
If that's the case, the easiest fix would be to delete the config files for the DE, log out, and then log back in. The config files should get recreated and your desktop should be functional.
Another test would be, before logging in, to use the "Session" icon on the login screen to choose a different desktop, and see if the problem occurs under it. I have Mint Maya on a machine and it seems to have included Cinnamon, MATE, Gnome Fallback, though I'm using Enlightenment right now.
Last edited by frankbell; 06-20-2013 at 08:52 PM.