The answer to this question, for Wolfgang as well as anyone else reading in, is
to add the following line to your autoexec.bat file
SCREENGRAB=YES
Now start 3D Studio and push the combination of Ctrl Shift & PrintScrn
buttons. A file name requester box will appear, allowing you to name the file.
Tips:
The captured image will be the same resolution as you have your main display
set-up in your VIBCFG.
Be sure to move your cursor off the screen (into a corner). It will show up in
the screen grab.
Lee