[Havoc_covaH]

I have found a temporary but workable solution to the problem for anyone else who has encountered this problem.

Just delete or copy all of your downloaded pk3 files and empty your MOHAA/main folder, then go ahead and complete the Spearhead campaigns. When you're done, just restore the files from your trash can or cut and paste them from a backup file.

I'm still trying to find out what certain pk3 file is doing the mess, I'll try to update.