Finally gritted my teeth and went for it. When it was offered I hit the F10 key, and....nothing happened. Black screen for a few moments then the dreaded OPERATING SYSTEM NOT FOUND.

It was working fine all day today till I restarted to update McAfee. Last time I restarted, it came back to life normally.

I'll take the battery out again, leave it till tomorrow, and I bet it starts back up like nothing happened. Good thing it's just my BF's toy.