So yesterday my iMac froze while using iTunes. I had to manually power it off. I turned it on again and it booted fine. I tried iTunes again and shortly after that it froze again. I manually shut it down again. I tried to turn it on once again and it won't load the desktop. It just stays at the grey screen with the apple and spinning thing. I am pretty sure I have to erase and install again, but I am not really sure on how to do it correctly especially since I can't even get to the desktop. My OS is 10.5.8 and the machine is only 2 years old and hasn't really given me any problems before.