Strange fan issue

I came home from my teaching gig tonight and my wife had been surfing with the new 20" iMac G5, the screen was blank and the monitor light was off. The fan was running full blast though. I could not get it to wake.
It was still on though, the light on my wireless mouse receiver was still lit.
I ended up having to hold the power switch till it shut down and rebooted.

Is this normal?

Did it again. I wasn't working with it for awhile and it went to sleep mode. When I tried to wake it the light stopped flashing and went dark. No response to keystrokes of mouse input. Then the fan went on full bore. Had to turn it off and reboot.
Any ideas?

I did a search and found this. It seems appropriate to continue here.

Last night I had the exact same problem. My wife wanted to check emails on the iMac when it should have been in sleep mode. She asked me how to start it up. When I went in the screen was blank, there was no power light blinking, it appeared to be off. However, the fan was running full bore. I had to pull the plug. After that it started up fine. I had run a software update if that means anything.

I have not been able to duplicate the problem after a number of tries.

Any insight?

TIA

Just a shot in the dark
Have you checked your Energy saver setting in system Preferences.

torchy said:

Just a shot in the dark
Have you checked your Energy saver setting in system Preferences.

Click to expand...

Only had it a week. I haven't gotten that far to mess it up. So it is still set at factory settings. What ever they are. I will keep an eye on it. Would this be considered a crash?