AV Macintosh: Blocks at startup or Menus Remain Down

I have a Power Macintosh AV computer and I'm getting strange behavior with the pull down menus. At startup, small black squares appear on the top of the screen which are evenly spaced apart by about 5 or 6 pixels. Menus stay drawn on the screen. For example, choosing the Apple menu and then the Special menu will leave both drawn on the screen.
This issue has been reported on Power Macintosh computers running either System Software 7.1.2, or System 7.5. We have also had reports on Quadra AV computers. This issue has been fixed with the release of System Update 7.5 version 1.0, and you should install it.

If you do not have access to System Update 7.5 version 1.0 use the workaround shown below:

We have found this problem will reset PRAM after a system crash when the colors are set to millions, and occasionally when switching to NTSC/PAL output on a Power Macintosh AV.

The key to resolving the issue is to have the Monitors control panel update PRAM and the System File.
Published Date: Feb 19, 2012