yes thats definatly a confusing problem… I spoke to my other buddie about vdms, and he has the EXACT same problem as you, so i gave him the same advice i gave you. And he installed dosbox, and everything works fine. SO i have a feelings vdms has a problem of some sort, trying to support newer hardware. SO it worked for him, so it should hopefully work for you. I also dont think there is much support for vdms, and noone is updating that program. (well i have not seen any newer versions, for over a year i think)
Whereas DOSBOX is an ongoing program, which recieves quite a bit of updating fairly often, by its creator, so support for newer hardware, should never be a problem with Dosbox…
Well that should solve everything.
Just let us know if it worked for you! Happy Sierra Gaming!