I was in the process of installing a computer game I downloaded (before you ask, I own the game, we're just sharing it over the network) when I noticed the computer was being really sluggish when trying to run anything else (Firefox/Winamp etc etc). So I canceled the install and restarted the laptop. It started the disk check on bootup and gave some error for the file (.iso) I was using to install (it said the file was "null"). I don't know why diskcheck started because I restarted normally, no crash. In any event, upon reboot I got a consistent barrage of windows system messages (the ones where you can choose to send/don't send). They would not stop so I restarted. Upon restart my computer has just been boggy/sluggish. The sound is really choppy every other few seconds, and every time I try to multitask two programs it either freezes up for a few seconds or just slows down dramatically. My AVG Antivirus says I've had a recent boot sector change and I have no spyware. Nothing fishy on startup. No odd processes. I'm about to fix my MBR and Boot Sector, but that's a last measure for me. Any ideas? I can't figure out what went wrong?