Hi,
As you said that it worked fine with NTVDM in Windows 2000 and XP, are we speaking about running it in Win 2k/XP on the same machine or on a different machine?
NTVDM normally passes through all I/O directly to the underlying Video Hardware, when in fullscreen mode, so there is the possibility that there is a compatibility issue there.
It would also be interesting HOW the DOS application changes the Video mode.
This can either be done via directly programming the IO registers of the video card or by just using the
BIOS INT 10h service for it. As the NTVDM usese the real BIOS of the PC for BIOS calls, it could be that the functions fo switching video modes implemented there do not work as expected.
Did you try the 32bit IO fix for the NTVDM? Modern BIOSes may want to use 32bit I/O, so the calls won't work correctly as NTVDM doesn't support the calls without the fix:
https://www.waldbauer.com/vb/showpos...2&postcount=14