I've lately experienced some (minor) problems with my A4k. If it locks up, running some crappy sw I personally didn't write :-), it keeps on booting itself constantly. However, if I connect and switch on my 1084-monitor it stops the constant booting-sequence and displays the guru-msg. This is very annoying since I don't have space for an extra monitor on my desks right now.
I belive the problem started when I accidently moved a cable from the audio-output and it touched the inner workings of the PSU resulting in a flash or two
The current hardware is:
Fastlane Z3
Cybervision 64
Toccata
X-Surf