Report it to support ASAP GOG never checks the forums.

I was just having the same issue myself! I have a boxed copy of the floppy version in my personal collection, and I think it might have a similar issue, but I don't remember the workaround.

I'm really disappointed in GOG botching what should've been a relatively easy release. Could they not get their hands on the more stable CD-ROM version of the game? smh

Atari would be the ones who would prepare the release.

I just tried this, the way to make the 'other' version of GS2000 work and avoid crashing was to apply the 469.085 patch to bring the game up to latest version, I just tried it with the GOG version, now doesn't crash going into the mission briefing. From memory, the patch also breaks the copy protection crack so you definitely need the copy protection sheet from the expansion which isn't included in GOG's release (woo).

Trying to give Atari the benefit of the doubt here, assuming this is the only way they could get their hands on a functional copy of Gunship 2000 and they don't have the resources available to mess around with dosbox, there isn't that much more work they'd need to do to make this stable and entirely working (it took me about 5 minutes, a few file copies and a few dosbox config edits and that's about it, but then I did already know the process to try).

A note about the crash, I saw it when going into the briefing of a new pilot in the middle east (i.e. first training mission), I did not see it going into the briefing of one of the 'premade' pilots in europe.