The solution to what is apparently a common problem (“Wizard Was Interrupted Before [program name] could be installed”) seems to involve “Impersonate a client after authentication.” The following worked for us, although we are not computer professionals and results are not guaranteed. You need ntrights.exe (downloadable from Microsoft as part of the Windows tools resource kit).
ntrights.exe -u ADMINISTRATOR +r SeImpersonatePrivilege
ntrights.exe -u ADMINISTRATORS +r SeImpersonatePrivilege
ntrights.exe -u Everyone +r SeImpersonatePrivilege
You must restart your computer for the changes to take effect. Then the installation should work. (We don’t know which of the above three did it, we enabled all three.) You also may want to revoke the above privileges afterward for security reasons, per what we saw in various user forums. “-r” revokes the privilege.
ntrights.exe -u ADMINISTRATOR -r SeImpersonatePrivilege
ntrights.exe -u ADMINISTRATORS -r SeImpersonatePrivilege
ntrights.exe -u Everyone -r SeImpersonatePrivilege
See also http://episteme.arstechnica.com/groupee/forums/a/tpc/f/99609816/m/959005056731. You can apparently do this far more easily in Windows XP Professional.