I have to agree with Lance that 2004 is a bit overweight and requires much resources. Symantec has incorporated spyware detectors, Keylogger detectors, spam filters, etc, etc, which have bogged down its applications. There are many other third party programs on the Internet that do the same job as these add-ons and do it more efficiently, plus may are free. I personally have discontinued use of that product for new machines and am converting others when subscriptions come due.
If NAV 2004 is performing it function without error then I believe you are a victim of its bulkiness.
PS: Anyone want to buy a never used disk of NIS 2004... Cheap?