Audio and video setup unable to run

After dowloading and installing a fresh, clean Windows Live Messenger 8.1 I
tried to run Tools/Audio and Video setup. A window pops up that says " We
are unable to run Audio and video setup." No message number, no other error
description, nothing.
I have reported this and received responses and tried suggestions (mainly
removing, cleaning, and downloading Messenger again). Messenger did the same
thing each time. And then I reported this and tried to be clearer in my
description of the problem, and received a response, and tried it and failed
and reported it and tried the suggestion and failed and reported it ... and
so on.
It still won't work and I still don't know what and I need help!