Recently, since using Ubuntu, I've been having a problem with my monitor being distorted, (color reversal) when coming back from screen saver. I didn't have this problem using Debian, or SuSe, or Mandriva....so I'm assuming that there is something about Ubuntu that is different. It's sporatic, happening only about every third time I come out of screen saver. I'm using gnome desktop, and am only using the provided screen savers that come with ubuntu. I have an nvidia 5600 video card,and a viewsonic 19inch widescreen monitor.

any suggestions?
thanks