From the earlier postings regarding the problems with applying the orginal version of the 3.! updater, I would guess that you installed the UFT on drive D after you did the one on Drive C.(The install procedure writes information into the registry file, and apparently, the updater uses that information to 'find' UFT.)
I believe you may be able to solve your problem by reinstalling ver 3.0 on Drive C.(BACKUP YOUR DATA FIRST!!!! Be careful to do an update and not a complete install-- normally that will not overwrite your data.)Then see if the updater will update the UFT on Drive C.