NAV....help :(

I am attempting to install Norton Antivirus Corporate 7.5 on a NT 4 SP6/Exchange 5.5 SP4 Server. I have reached step 7 of the Administrator Install(Install Norton Antivirus To Servers). I selected the server and ran through the steps. It hangs on the actual install of the files. Says it is "Copying Files" and "100%", "no errors". Yet it goes no further. I have checked all the usualy suspects(Knowledge Base, NAV Tech Support, and Google). I have unistalled and reinstalled several times to try to overcome this. Any help would be appreciated.

You may want to stop all the Exchange services and any other misc services and try the install again. Anti-virus programs don't like to play nice with installed and running applications.