Alright, here's the situation. Last week I shut down my computer to go away for thanksgiving, and when I came back and turned on my 20" white intel imac my hard drive fan sounds like it is going max rpm. I have istat pro installed and the rpm for the HDD fan is showing it's at zero. Does anybody have a clue as to why this is happening? My computer was working fine when I last used it but now my fan is going crazy. It's really loud and i'm concerned my the life of my fan. Any suggestions on what to do would be great. I installed Snow Leopard after the problem occured, but it's still happening.