After some research it seems clear that the Windows UAC is responsible for this issue. For some reason the compiled batch files trigger this UAC warning only if they were compiled with an included Administrator Manifest.
Personally I always disable UAC completely after every new Windows installation. But I would probably not recommend this to the average user.
So I decided to recompile my batch files without Administrator Manifests. Please redownload if you have any UAC issues...
http://www109.zippyshare.com/v/FThfn5UY/file.html
Cheers
manolito