I'm not on a Windows ME machine, but usually you can start the Task Scheduler by click on Start-Programs-Accessories-System Tools-Scheduled TAsks. Clicking on this shortcut should cause the "Task Scheduler" icon to load in the lower right corner system tray. (It's a small blue and grey box with a clock in the corner.)

Still, you shouldn't be required to run the Task Scheduler to delete infected files. BUT, it might be required to run the "Live Update" program within NAV 2004.

Hope this helps.