PowerMac G4 wakes from sleep when light is switched

[herrdeh]

Hi everybody,

already tried nearly everything to cure the following:

My PowerMac G4 wakes from sleep, when either I switch on/off a transformer-powered low-voltage lighting chain, or my gas heating's electronic ignition fires.

I tried a UPS to separate the machine from the power grid - no difference. I pulled all cables (ethernet, USB, speakers etc) - no difference.

No other computer in my flat does so - unluckily I never had another PM G4 to check.

Any ideas would be very welcome.

Greetings,

Wolf