I think my computer's kernel is panicking. The key board lights flash and the computer locks up...and this happens after the computer has been running for an hour or so. It doesn't matter what it's doing -- it could be idling and it will still happen.

I ran memtest86+ to make sure there wasn't any memory issues and the tests came back clean. Hardware shouldn't be an issue -- it was my desktop before I loaded ubuntu on it and all the hardware was working last week.

What am I looking for in system logs? I haven't found anything which looks critical. Is there a way to fix it?