Well it is. I cannot make new maps anymore (all the resources are messed up), I cannot play random games anymore (all the resources are messed up)
Stormbind,
I had the exact same problem before. It is actually easy to resolve. Somewhere there is a thread with the info, but I don't know how to find it.
1. Go to the CivIII/Art folder and find the folder in it called "resources storage".
2. In it find the folder called "gotm21_before"
3. That folder contains 2 files: resources.pcx, and resources_shadows.pcx
4. Copy both files and paste back in the CivIII/Art folder. They will write over the current files.
5. Play your original version of Civ with random maps and such. I have had no problems with this.
6. When you want to play GOTM, copy the files from the "gotm 24" folder into the CivIII/Art folder to write over the original files. You can do this as often as you like, and it will take you less than 1 minute.
Best of luck!
P.S. I agree with the earlier comments that the original GOTM schedule should have been kept, and the C3C GOTM added mid month. It was very disappointing not to have the new GOTM, and the C3C people wouldn't have minded since they didn't expect it anyway. Hindsight's 20/20, so it's probably clear now that this approach would have been both simpler, and created very little frustration on anyone's part.