Been on a Mac in one form or another but never saw this. It's not even mentioned on the apple.com site under startup problems. Started up on my eMac and got this blinking blue dot that looked a bit like earth in a gray square. Whole think was about an 1" square in the middle of the screen. The startup tone was normal. Zapped the PRAM and was good to go, but does anyone know what happened? Thanks!