Although every PC needs a good virus checker, NAV 4.x is not a good choice. It conflicts with ArcServe tape backup on a Netware 4.11 server. Simply trying to erase a DLT tape or restore a file from tape will cause ArcServe to hang frequently. Unloading (F10) the NAV NLM unfreezes ArcServe. It sure beats bouncing the server. Don’t forget to load the NAV NLM after ArcServe unfreezes.
Also, NAV 4.x (running on Windows 95 Version B) has to be disabled to install software. Otherwise, you get a mysterious error something like Iss_se, which means it crashed during the install shield. Upgrading to NAV 5.X or higher seems to help. However, even NAV version 5 or 7 slows down opening a file on a WAN. A PowerPoint file takes about 2 seconds to open with NAV disabled. It takes about another 60 seconds if NAV is enabled. Sometimes disabling NAV 4.x still prevents Windows ScanDisk from running unless you boot to safe mode. I wonder if McAfee has similar problems?