Oh, and it had nothing to do with HiJack - my old player did it with and without HiJack installed.
As far as I can remember, there were no error-messages on the boot-log, however, the player process itself ran extremely high. Load averages topped 8.0 across the board.
(Now, thinking of it, I think that on mine, at least, you COULD get into the Hijack menu..)