mac laptop, projector resolution, detection problems

I have a white mac laptop which I have attached to a projector with the DVI to VGA adapter. If the computer is turned off or if it goes to screen saver, it doesn't keep the resolution settings and I have to reset it, detecting the display and changing the resolution. My macbook pro did the same thing when I was presenting to a group. Sometimes this even happens in what seems a random fashion. I've used a PC on the same projector and that never happens! What is going on? Is there any way I can fix this problem? It happens on different projectors as well.

Well, for a start, turn off display sleep and screensavers.

The reason this is happening is *likely* to be the DVI to VGA adapter. PCs tend to use VGA so you have VGA-VGA and there's less chance of a communication issue.