I know G4s are infamous for booting problems, but I've read about them and mine seems a bit different. When I start up, everything goes as it should, the apple logo comes up, the little spinning circle comes up below it, the fan comes on, it makes the starting up chime sound. The problem is when it comes to the loading bar afterwards. It just stays blank instead of filling up with blue. My mouse comes up on the screen and moves, but the loading bar stays blank. Suggestions?