I assume you are playing Civ3 1.29? If not then you *shouldn't* be getting this problem.
There are two files: resources.pcx and resourceshadows.pcx in your \Art folder. There should also be a folder called 'Before GOTM xx' that contains the versions of these two files that were replaced. Swap these files back and your random games should play nice again. You will need to swap them back again if you want to play another gotm.
There ought to be a Readme somewhere in your installation covering this subject, but I don't know whether this is (still) the case .. I don't do Windows installers.
To avoid all this I keep two separate copies of the complete Civ3 folder on my hard drive, one modded and one unmodded, with separate shortcuts to the two .exe's so that I can launch either (or both).
There are two files: resources.pcx and resourceshadows.pcx in your \Art folder. There should also be a folder called 'Before GOTM xx' that contains the versions of these two files that were replaced. Swap these files back and your random games should play nice again. You will need to swap them back again if you want to play another gotm.
There ought to be a Readme somewhere in your installation covering this subject, but I don't know whether this is (still) the case .. I don't do Windows installers.
To avoid all this I keep two separate copies of the complete Civ3 folder on my hard drive, one modded and one unmodded, with separate shortcuts to the two .exe's so that I can launch either (or both).