Recently, I had the pleasure to work with a client on a backup issue (coincidently, I love Backup Exec). But their was a problem… When installing Veritas Backup Exec CPS Server 11D make sure that Symantec AV is version 10 or greater before running the upgrade. When SAV 9 is installed the CPS server installation fails and your systems is left in a foul state. The best thing to do is to remove CPS and NAV, then start over. You will also lose your backup jobs if this is done. So, save yourself the headache and make sure you always have up-to-date software installed!
If you are having trouble removing nav try NoNAV.exe from Symantec. It rips out all of the junk left over by a failed NAV install and leaves your system is a pre-NAV state.