Outlook crashes with Mcafee VirusScan 5

I have Outlook 2000 with Mcafee virusScan Installed.VirusScan has integratd with Outlook 2000 for one click scan and scan property changing from within Outlook by 2 buttons it has added next to Outlook Help button.My problem is whenever i open Outlook with e-mail scan running and system scan running it runs fine but when i run Outlok with e mail scan running without System Scan,Outlook crashes while exiting the program.Why is this so??