(apologies, kipwil. This is a side note for wha.)
Some interesting observations on this by markarich over here, wha:
My thoughts there:
In the normal course of events, SoftwawareUpdate.exe is not set to run as an administrator.
In the normal course of events, if SoftwareUpdate.exe is set to run as administrator, then the Apple Software Update.lnk compatibility mode tab should also be showing that ASU has been set to run as an administrator. So it's not clear why a discrepancy was being seen there.
(Granted, if we've dealing with weird permissions **** here then the symptoms ought to be a bit weird, by definition.)