Hi, Sam. I hate problems like that. :-(
Did it occur before OneCare was installed? When the PC freezes, is it black screen frozen, mouse frozen, or all activity frozen? I suspect that it has nothing to do with OneCare, but I wouldn't rule it out, either. It may be a driver problem, or it could be a memory or hardware issue, particularly since it is random. Is the PC running any programs or is the PC in use when it happens or is after a period of inactivity? Could it be a screensaver issue?
-steve