NA VirusScan causing shutdown error

I'm working with an ITS group in a hospital, and we've run into a little snag with a few laptops. We recently pushed out the Network Associates virus scanner (v4.0.3a). Almost immediately afterwards, two NT laptops started having problems on shutdown. The machine would get to the "Please wait while saving data to the disk" message box, and would then give one long (and very loud) beep. I have heard of this being an issue with the virus scanner before, but I was wondering if anyone had run into this. Thanks,
Scott