Posting this in case others are having the same problem or someone knows where the problem lies.After spending hours trying to install FSDiscover! Demo and FSUIPC 4, I found the reason they wouldn't work was because the modules were not being written to the dll.xml file. However, MyTraffic X had no problem installing as it was supposed to. After I manually entered the add-on modules for FSDiscover! and FSUIPC 4 to the dll.xml file they both worked fine. I'm guessing this could possibly be related to the Vista RC1 that I am using but I won't put the blame there until I try it all again with the retail version. If anyone knows for sure where the problem lies, please post.

My guess, and its only a guess, is that the installers are using a semi-hardcoded path to where they think the .XML files should go instead of getting the path from the OS (although I can't imagine Pete making that mistake :-> ). Under XP, the path is C:Documents and SettingsUSERNAMEApplication DataMicrosoftFSX whereas under Vista its C:UsersUSERNAMEApplication DataMicrosoftFSX - ie if they are assuming the C:Documents and Settings part and then appending the current logged in username to build the path, then this wont work on Vista, you have to use the OS API function to retrieve a path based off one of the CSIDL_xxx ID values.