I'm afraid to hear the possible truth to this question, but...
The screen on my eMac contracts a bit in size for a fraction of a second to a second. Seems to only do it when using a browser, not just when my slide show is running or if I have a solid color background on the desktop.
It doesn't always do it, but seems to happen after it has warmed up a bit. Doesn't seem to matter if I put it to sleep or shut it down.
I've read a bit near to this subject but none have had exactly the same problem. They had jittery desktops for the most part.
I'm afraid that it might be the motherboard and or a chip. But it seems that replaciing it might not be cost effective as most repairers won't replace the affected chip, just swap out the logic/motherboard.
This started happening soon after switching up to 10.3.9
Any ideas will be greatly appreciated.
Thanks for your attention to this matter,
eMac 1 GHz, 1GB RAM, OSX 3.9, Safari, Opera, Firefox, Camino, Mozilla; used in that order of preference.