If you used the Mirage UI, these are the files below that need to be edited to fix the pop-up boxes when you load the game. I'm sure Mirage will post a fix soon, but in the meantime, to load your custom UI:
Open with Notepad, Change (in 2nd line of HTML) number from 49054 to 48416.
(VISTA x64 Filepath) C:\Program Files (x86)\Funcom\Age of Conan\cd_image\Gui\Customized\Views\
**Edit - This will work for any modded UI files, just write down the files the game tells you have the wrong version, and change them to the appropriate version. Same instructions, different files.