I made a nice clean install of Mint yesterday (I was an unhappy Ubuntu user) and love everything---except every so often, my desktop locks up solid.
When it happens, I cannot select anything in any programs, open the GNOME 3 menu (or use the relevant keyboard shortcuts) or really anything else. The mouse still moves, however, and I can still select windows. I can also still switch to virtual terminals and access the machine via SSH. The problem can be remedied by pressing Alt-SysRq-K or running "killall Xorg" and restarting the entire desktop. However, after restarting programs and waiting about fifteen or twenty minutes, it does it again.
After an afternoon of letting the computer idle and checking to see if it had crashed, I determined the culprit was Banshee. After playing about five songs, it would cause the freeze. The system ran rock solid for a couple of hours without any music playing, and is currently running fine with VLC playing music, so it's not the audio driver.
How would I go about trying to fix this? I couldn't find anything relevant searching Google. If it matters, I'm using the 64-bit version of Mint 12.