A few weeks ago when I booted up, a got the message that said I needed to use my back-up disk. I re-booted and everything was okay. Then on Saturday, I heard a very loud whirring noise coming from the PC, I re-booted and got a blue screen that said "unable to write to drive "C', re-booted again, and got registry checker, and then backing up sys files. I fooled that up with a thorough scan disk including surface scan and found no errors. Now I'm up and running, but it I can still hear the whirring sound coming from my PC. It's not as loud as the initial sound, but nevertheless quite annoying. Any opinions would be appreciated.