I woke up this morning and my iMac wouldn't wake from sleep. then when it finally did I had a all black screen with a few red pixels at the top. the imac wouldn't do anything so I had to hold the power button down and restart. now when I try to turn it on, I hear the apple sound, I get the grey screen (10.4) with the white apple and a spinning circle, then it goes to a light blue screen and just sits there. I still have a cursor and it moves with my mouse. any thoughts??? I'm thinking maybe my harddrive failed.