As you said it worked on XP before, presumably you mean you're now on vista? If so I assume problem is to do with it trying to protect what it sees as 'program files'. Look for info about modding when using vista - I think you need to turn UAC off and/or not install the game under the program files directory.

You could try copying the bin files and alpaca's converter to somewhere outside the program files folder and see if it will work there.



If not there were some of the .txt versions of the files released here
https://forums.totalwar.org/vb/showthread.php?t=73971
but they must have been for an early version judging by date. Can try and find you a v1.5 VnV's file if that's what you're on. (normally you're not meant to send any unmodified game files - but I assume as the earlier version of them was officially released it would be OK in that instance ? )