trouble with sleep

[memphisbrian]

MODEL iMac G5 (Rev. A)
PROC 1.8 GHz
RAM 768 MB
DRIVE 80 GB

A few weeks ago, my iMac started acting funny when it went to sleep. Whether I put it to sleep or it falls asleep on its own, it doesn't always wake up. And a few times overnight, it apparently goes crazy and starts spinning the fans at full blast.

I've tried deleting preferences, zapping the PRAM, running the hardware test (everything's fine). I also tried re-setting the PMU, but I'm not sure if I did it right.

I have an external Firewire drive that holds all of my iTunes music, and I believe it does it even when the drive isn't connected.

Based on a little online research, I think it could be related to upgrading to 10.4.7 but I'm not entirely sure.

Thanks,
Brian

 

[Mikuro]

I've had this exact same problem, and I've traced it down to external devices. I've found that once I turn on my external DVD±RW drive, I can't turn it back off without this happening (unless I reboot once it's off).

Once it gets into the the bad-sleep mode, I have been able to wake it, although not with a 100% success rate. Turning on/off my FireWire DVD±RW, [un]plugging my gamepad, pressing my Mac Mini's power button, and hitting command-control-power on my third-party keyboard (which usually forces a reboot) all sometimes wake it up.

I first saw this problem with 10.4.0, IIRC, and I haven't seen it in several months (I assume because I've changed my habits regarding external devices).