System lockup during NAV update

I recently purchased installed AntiVirus in three machines. One is Win 7 64bit and two are Win 7 32bit. Yesterday the 32bit machines started freezing up about 5 minutes after booting. I tried a number of fixes including: 1) running the virus scan in both normal and safe mode to see if there was a virus (there wasn't), 2) turning off Acronis non-stop backup, 3) removing any unnecessary background tasks. When I tried to run the Norton Updater it got to "Installing 4 of 8" and didn't make any further progress although the progress bar continued to move - until it, too, froze. The version of NAV running on the two 32 bit machines is 20.2.0.19. I got one of the 32 bit machines to run fine by simply uninstalling NAV. I haven't tried that yet on the other.

 

The 64 bit machine works fine and updates fine. Any suggestions?