I have a new 17" core 2 duo imac (2.16 gHz, 1 Gig RAM) and my machine has just recently begun booting about 5 times slower than it did in the first week when I had it. This started after I was watching a video I had just finished editing and the computer's fan suddenly went on like a jet engine - which it hadn't ever before. I turned it off quickly (I've had some friends who've experienced overheating problems from apple, so I wanted to be cautious), and since then, my startup time has been pretty bad (comparitively). When turned on, the grey screen appears (without the apple in the middle), and just sits there for a good 45-60 seconds before there is any discernable action coming from the computer. This comes from a previous startup time of less than 20 seconds. Any thoughts?