OK. This one really scares me. On my monitor, occasionally, flashing greenlike light, irregular interval, sometimes I have sessions without it happening at all - today it turned up as I turned the iMac on and left it for a coupple of minutes... . It flashes a coupple of times then it disappaers - what the hell is it? Software conflicts? Hardware? Electric phenomenons?
iMac/B/32RAM/RAM & Speed doubler etc etc.