hmm... wonder if UAC or other vista/win7 program diverting features kick in.
I've written some softwares that worked just fine as useronly installs, but I built them as such from the scratch.

anyways... was reading a bit on it.
one example: http://stackoverflow.com/questions/1002709/detecting-registry-virtualization

basicly, you are screwed \:\)
_________________________
!

download KiXnet