Hi.

On Windows XP our emacs version 21.2.1 behaves strange after having worked for let's say 20 minutes.
The severity is not always the same, the enclosed picture shows a very "mild" situation (only the frame is corrupt, with some extra stripes).
Often the complete display gets scrambled.
* M-x redraw-display solves the problem temporarily, however, after a much shorter period the same thing happens again.
* Turning the hardware-accelerators lower (desktop/Properties/Settings/Advanced.../Troubleshooting) solves the problem!

We work with Smallworld GIS and use a specific mode for this.
It happens editing files in the special mode and running the Smallworld GIS from within Emacs at the same time (external process).
It was not tested with "plain" emacs (-q --no-site-file) since that makes emacs nearly useless for our work and we'd have to work for some time.
The problem *did* not occur with emacs 20 and *does* not occur on Windows NT and Windows 2000.

Regards, Geert Ribbers