About an year ago, I wrote a relatively long and detailed post about UAC. One
thing I failed to mention is what happens once an application that you have started
requires acknowledgment yet the request is ignored.
UAC has a timeout of two minutes. If no acknowledgment is received within those
two minutes, the action fails silently (same as if you would have declined).
The only thing that bugs me here is that you have no notification/logging of what
just happened. If you were away from the system while the UAC prompt appeared
you might not understand why something failed…