You will have to reinstall TATW I`m affraid

. Follow these steps:
THIS IS IMPORTANT:
disable UAC (
http://www.twcenter.net/forums/showt...59#post8287059) go to section
`How to fix it` and apply
step 3.
Now procced to this down:
You have to reinstall TATW ( but first
uninstall MOS of course by using START \ All Programs\ MOS v1.4\ Uninstall MOS v1.4), then uninstall TATW by using Control Panel Uninstall program, after that, delete Third_Age_3 folder in C:\ ..\SEGA\Medieval 2 Total War\mods ( or if it was installed somewhere els, delete it there) and in virtual store C:\Users\[user name or your PC`s name]\AppData\Local\VirtualStore\Program Files(x?)\Medieval 2 Total War\mods (if u can`t find it, then it is hidden, so follow this
How to Unhide hidden folders on Windows: http://www.twcenter.net/forums/showt...59#post8287059).
After deleting these Third_Age_3 folders( if there were any),
and disabling UAC, click on TATW 3.0 part 1 of 2 installer, when it asks you where to install it, if you know the CORRECT path where you installed Medieval 2 Total War and it is the same as the installer points you to by default( C:\ Program Files (x86)\ SEGA\ Medieval 2 Total War ), then procced with installing.
If you installed in another place, then browse the installer to the Medieval 2 Total War folder.
Then install TATW 3.0 part 2 of 2 using the SAME installing path, and I would advise you to install TATW 3.1 patch (using the SAME installing path ofcourse) and then try the game does it work, and can you open campaigns, for battle crashes disable daylight savings (Using Windows 7, 8 or Vista: Control panel > Date and time > Change time zone > uncheck "Automatically adjust clock for Daylight Saving Time").
If TATW 3.1 works, procced with installing TATW 3.2 patch (using the SAME installing path ofcourse).
Then Install MOS in your Third_Age_3 folder ( I would advise you to run all MOS Installers as Administrator).
Be sure to check the INSTALLATION PATHS CAREFULLY.