Hmm...
That sounds strange, for sure. Unfortunatly, I don't know of any good A3000 hardware diagnostic programs. If you find one, let me know. ;-) I think you're on the right track suspecting hardware, though.
My first thought is to try removing all Zorro cards (X-Surf, etc) and give it a go. A bus error or something of the like could be causing random gurus. In fact, a faulty X-Surf caused very similar problems on my A4000. Even if the cards themselves are ok, you might not be running a proper Buster revision for a card to function correctly, or there may be some other modification that needs to be performed. There were several that could cause system instability.
If the system is still acting poorly without the Zorro cards, I might next examine the power supply. Obviously, if the system is getting poor power, it can lock, crash, guru, or do all sorts of other strange things.
Let us know if either of those two areas turn up anything.
