i've been working on this problem again, to no avail sadly but i wonder if i'm getting closer.

This is what i have just done:

1, wiped C clean except HDDRIVER (properly clean, only one file, HDDRIVER.SYS)
2, installed nvdi v4.1 (ET4000 version)
3, installed FreeMINT again from fresh

boot order is:
nvdi.prg
slct_dev.prg
mint030.prg

I also have a good nvdivga.inf file. I'm not using redirect.prg at the moment as it's not nessecary to get it working.

I can boot and select TT-Med from slct_dev and boot into mint/terradesk with nvdi running using the built-in video output.

I can boot into TOS in either built-in TT or CrazyDots video modes with nvdi.

I can't boot into mint/terradesk when i select any of the CrazyDots modes.

I have tried different entries in the xaaes.cfg file for the 'VIDEO' parameter, nothing makes any difference.

So Mint/NVDI/slct_dev all will work together until nvdi tries to use the CrazyDots card under mint, so there must be something that nvdi is trying to do that mint or Xaaes does not like? I'm running without memory protection so it's not that. Could there be any reason why mint or xaaes might cause problems accessing this kind of hardware?