Imac G5 Sleep


I've seen this problem posted before, but not seen a reply

Basically if I tell my iMac G5 to go to sleep, it sleeps.

If the energy saving settings kick in and the Mac goes to sleep by itself, the screen goes black and the Power Light on the front lights up. However, it doesn't pulsate and the fans still keep on running.
It wasn't always like this.

is this a problem?

MacOS X 10.4.2 (Ambient light sensor)
20" iMac G5
1 Gb Ram

Many Thanks

As A follow up, I've isolated a cause. This seems to happen if the other computer connected to my ADSL router has been switched on during the same session. If just the Mac is started up, all is as it should be.
I seem to have effected a cure for this. Apple's support Chat gave me a whole host of options, which finally culminated in a re-install of OS X. None of it worked, however.

I came across another discussion of this problem and one solution was to delete a number of preference files from /library/Preferences amongst other places.

The key file for me was in my own library: /Library/Preferences/ByHost/.GlobalPreferences.plist

however, this is a hidden file and only named by Spotlight. You can't easily open it or delete it.

My solution was to FTP in from my RISCOS machine and delete the file using that. I dare say it is probably possible just to use Terminal to do the same, but I'm not sure of the commands.

Anyway, this worked fine and the problem has gone away. My iMac now sleeps.

I thought I should include this info in case this problem troubles someone else, as it seems to have done for several others.