Oh, No...you toasted your Motherboard! Haha... Anyway..
Betting it was validating as Thomas commented.
May I suggest adding this to your C: and Startup-Sequence at the very beginning?
http://aminet.net/package/util/cli/checkdrv
It's great program for checking drive validation. It won't let the boot process continue until all drives in a list that you enter are validated. It shows text so you know what's happening vs a blank screen and possibly checking Hard Drive light activity.