if this is that level im thinking of, I believe that crash always happened for me back in the day. Never necessarily found a way around it that I can remember, I think I had to unlock the rest of the levels in the game files/console to be able to continue to next campaigns

Cheers for replying, I somehow managed to get it working by loading a previous save I had on that mission and was able to discover the resource zones etc without it crashing. I deleted a file or two in the game folder marked "old_Plants.dta" and another called "Plants more recent.dta" that are not in other versions of the game, just the gog version. So that may have helped.