Hmm before I thought it was a Vista issue.
I install a fresh M2TW on my XP system. I had the exact problem in which every time I start a battle it crash.
I don't even get a shortcut icon. I must go to the folder to run RTJ:Terra Sancta. So I did the "--io.file_first" on the crusade shortcut.
Is it something up with the installer? I thought it was click the installer and that's it.
I had a fresh install. With Kingdom/Patch. I wonder how some player get theirs working. So strange I had the same error on two system.