Problem is what it says on the tin; Frequent but not consistent crashes mid-level and when loading a save or level. Running in 1024x768 with all the checkboxes in Advanced Options unchecked (with the "enable X" boxes checked as by default the game would crash as soon as I tried to start a new game).
I gotta say, between this and the appalling state of GOG's Interstate '76 release I'm gonna be hesitant before I buy any more non-DOSBox releases here. :/

If you are in the Museum levels, this is the game itself crashing.
Always has been this way.
Once you get past that level, the crashing should stop.

Nope, the second level, Pickman St. Station.

Well! Bizarrely enough, reinstalling the game and this time electing to include the Nightmare Levels in my installation fixed the problem, and I'm having a blast with the game. Weird!
Markin' you as the solution since I can't mark that I solved it myself and you were nice enough to wish me good luck. :)
I actually breezed through the museum crash-free. @_@

Sweeeet !
Hope it works as well for me.
:D
Glad you got it fixed.

It's not unlikely that the base game has some crash issues that have been solved with the expansion.