🤣 you need to build some silos!

Nothing to do with those silos : you start out the first mission with 1000 credits. This is enough to build your first power generator and refinery. If you read my OP, you would've seen that I just started building my first refinery. Upon saving and reloading this, the credits drop to 0.

You've either found a 35yo bug you cant find on google,
OR you're doing someting boringly normal.
Odds are on normall

As someone who has played Dune II countless times, I had to try it, as I also don't recall this bug, but I also don't recall having ever saved during the construction of the refinery either.
Mine is the CD version (1.07) and I tried it with the Harkonnen. Saved during the construction of the refinery, and then tried loading it. My observation:
- When loading from the main menu, the credits drop to zero and I get the same message.
- When loading from within the game (e.g. directly after the credits dropped to zero), the problem does not occur and the construction of the refinery continues.

Yes, some sort of bug. Alas Dune II had its fair share of them.

@myne : me doing something boringly normal? Never! 😀 So I'll just go with "found another bug", makes me special and all giddy inside.
@Kalle : I've completed all 3 campaigns when this came out but I also never saved during the construction of a refinery. And only stumbled upon it as I was testing it with a focus on those shaders. That being said : I was able to replicate the same behaviour :
1. it crashes if you load from the main menu
2. and it doesn't and the refinery indeed completes as normal

The game sure had quite some bugs (I recall one or two) but I think I'll just deal with them and go through the game once more 😀 Thanks for the help!

I was able to reproduce the bug as well. I think that maybe it was known already, albeit it's very rare and not mentioned often, for obvious reasons.

For other bugs, you might want to use the unofficial patch. Please note that due to how modern browsers work, Chrome and others may silently block the download because the file is on a server that does not support HTTPS. You'll have to right-click the download link and select the "Save link as" option, or use a download manager that does not suffer from these sensibilities.