I don't know what is the reason of this and what this mean, but it happened under DOSBox with voodo2*.exe-cs only (running directly from OS doesn't give that error). The only thing that I can do with this is to hide output by redirecting it to nul (voodo2c.exe -novoodoo -hires >nul). Voodoo execs used by GOG/Steam are latest (beta) execs and those execs are also used for software mode. But there is a carma.exe which is created to work in DOS without 3dfx in software mode which doesn't return such error.

I squeezed decent performance in 3dfx version. And software mode noticeably slower.

I thought there may be community fix or something else.

Looking further this is interesting. DOS4GW is a DOS extender. Version included with C1/SP is older one and have memory related bugs, so it's recommended to use more recent version or replace it with different DOS extender, which should increase game stability in general. I have tested this a bit, but always something strange happened on exit (DOSBox hang or quit, however quitting may be acceptable).

OT: Software mode is so slow in DOSBox, but fortunately Windows 95 executables (not depending on DOS4GW) working fast without DOSBox - look for 95RPP.

For DOS4GW.EXE problems, you should look at http://maximumhoyt.blogspot.com/2008/12/dos4gwexe-version-201a-and-alternative.html

The simple fix is to replace DOS4GW.EXE with the replacement that can be found at http://dos32a.narechk.net/index_en.html and just rename DOS/32 to DOS4GW.EXE and replace the one you have.

After replacement, my DOS games ran smoother with no memory glitches.

GOG should consider doing the same thing with thier games that use DOS4GW.EXE.