I'm not sure what's causing this problem, but in the last day, it has gotten so I can't even use my computer any more. The first time I noticed anything, I had just upgraded to iTunes 5, and noticed that every once in a while the song I was listening to would cut out, only to pick back up again a few seconds later. The pauses gradually increased in length. A few days ago I noticed the same thing happening anytime I tried to load a Quicktime movie in Safari. A pinwheel would come up and hold everything up for 20 seconds or so, and then the download would continue, albeit much slower than usual. Then Safari itself started getting these random pinwheel lockups, then iChat, and now Finder. Sometimes they pass after about a minute or two, and other times I have to turn off the computer and reboot, only to have it happen again. When I last used my computer, it was getting these every minute or so, and after being on for about 10 minutes, would lockup entirely. During the freezes, I can hear a rhythmic noise coming from somewhere in the case in groups of 3 or 4 pulses. I have no idea what could have made my perfectly functioning computer degenerate so quickly into a completely non-functioning one, and I would greatly appreciate any feedback anyone can give. Thanks.