Mint locks up

[wharris]

I have been using MINT for a couple of weeks now have used both UBUNTU and KUBUNTU for awhile with not to many problems. I like MINT as multi media seems to work better. However, I have had a problem with look ups. If I walk away from the computer for awhile and come back the screen has shut down and nothing will start it up again, I have to power down and reboot. Also sometimes when moving the cursor around it will just freeze and again I have to shut down and reboot. Any ideas?
Thanks

[clem]

It looks like a graphic card problem...