Most times when my monitor goes to screen saver and I bring back Mach3, I only get a partial screen, ie some elements are missing.  I can get the whole content by minimizing then restoring the screen.  More of an anoyance than a problem.  Is there a way to correct?

Quin

Yes, turn off the screensaver. You should never have a screensaver running when using Mach3.

Is there another, more serious, reason for having the screen saver off when running Mach 3?

Quin

Yes, it can cause your machine to stutter, or stall, and lose steps.
Absolutely nothing should be running on your PC when Mach3 is running.
Screensavers and power saving features are the worst offenders.