1) The graphics side of things works, although about the lower 1/3 of the
screen appears to be truncated. The mode is identified as VGA, with
640x480 pixel resolution, which is correct as far as I can tell. I am
using a Matrox MGA graphics card.

2) When switching to text mode from graphics mode, the screen goes blank
and no text is displayed, even though some is written to the screen. The
program switches back to graphics mode without problems, and the
remaining graphics screens are displayed correctly.

The above program worked fine under MS-DOS, Windows 3.1, Windows 95 and
Windows 98 (and I think Windows NT 3.5).

Can anyone suggest a fix to the problems that I am experiencing under
Windows NT 4.0?

Any suggestions are most welcome, as I have an application that regularly
requires switching between text and graphics mode, and then back to text
mode. On the first switch back to text mode, the text is no longer
visible, and never reappears when switched back to text mode at other
times. The application seems to work just fine, apart from the lack of
text display.

Note that the problem occurs irrespective of whether I just use the
RestoreCRTmode procedure, or I do call to CloseGraph with a subsequent
reinitialisation of the graphics mode using InitGraph.

Is there a fix to the graphics runtime library that will get rid of this
problem?

After reading your post, I tried setting the text mode foreground and
background colors after the call to ResetCRTmode. This had no effect
whatsoever.

I was running the program in an NT DOS window. When the graphics mode
starts up, the window goes into full screen mode. Starting BGIDEMO.PAS in
full screen mode does not seem to have any effect either.

Thanks for your response.