klappis: Sorry for a late reply but does that really help for you?
dr.schliemann: Honestly speaking, I haven't tried this myself: it's a general advice when a DOS game crashes reporting a memory error.
I am not very sure increasing DOSBox memory over 16 MiB does really help...
https://www.dosbox.com/wiki/Dosbox.conf - however manual does not mention this as an issue... maybe worth trying anyway.
I do have the same issue from time to time... even early in the game.
(I do not use GOG DOSBox, I have my own install)
Maybe it is worth trying other flavors of dosbox? like this:
https://dosbox-staging.github.io And one more point, I am pretty sure when I was originally playing this game on some Intel Pentium hardware
it was crashing from time to time as well. It might be just unfixable bug.
and to stop the error message from disappearing just remove exit command from your shortcut and your dosbox.conf
Let us know if any of that stuff helped you. :)