OK my G5 has a sense of humour!
This morning it was dead as a dead thing that has started to smell bad, so I go off to work thinking really bad thoughts and when I come home it is still dead. so then I post on here using my iMac telling you guys my bad news and then go back to my baby to see if I can fix it and guess what, the little bugger started up as if nothing was wrong and presented me with the innocent little logon prompt!
I have left the cheeky blighter to download some Mp3's and come back to my reliable iMac to post this.
Hmmm ... the G5 powered up fine but refused point blank to respond to the CD eject key (it probably figured I wanted to use the hardware test CD) so I accepted the GarageBand upgrade it offered me (39M download to upgrade!) and then rebooted. Now everything seems fine, that's the last time I ever put it to sleep again!
Maybe it got upset when I put it to sleep last night but the fan noise was driving me nuts (yesterday was a particularly hot day and I left the window closed, maybe it wants me to buy it some air conditioning

).
Amen-Moses