Funny you should mention Katrina- at this point I'm not sure if I named my cat after the hurricane or the 'cane was named after her (I tend to think the latter but I've been wrong before. )

yep i got one doing the same thing: in my case I'm convinced it's the hard drive but I haven't swaped out the hd to confirm it. If you added a higher level video card for example and then it exibited problems you might be looking at upgrading your power supply (if you are drawing more than it is rated to supply that could create the problems you describe)... for a few bucks you can replace the cmos battery too. and heavens to betsy; it could be a virus donchaknow?  

you might also scan your disk for problems; goto:
MyComputer:select the drive you wanna check:Files:properties:errorchecking:check now:scan

best of luck ! !