Hi,
I know this is an old thread but in case anyone else comes looking for the fix, I just had the same problem when I installed this. The problem is in the exe.xml. The installer adds and extra entry into the path. Instead of listing the path (on my machine) as F:\FSX\Modules\FSXSave.exe, it listed it as F:\FSX\Modules\FSXSave\FSXSave.exe. Once I corrected the path, it worked correctly.
Hope this helps,
Wayne