The similarities are there, but my machine locks up just after I see the desktop and the clock appears (when the startup apps would normally load), and I have no opportunity to even click the start button before everything is frozen.

I do have ZoneAlarm on all 4 machines, as well as WinPatrol, and SuperAntiSpyware (and 6.0.1 is still working just fine on the other three machines).

After reading through the other threads, I did attempt to reinstall 6.0.1 using custom install and just unchecked the Behavior Shield, and the WebRep. But even without those two opotions, the computer still locked up on reboot. I had to boot to safe mode to uninstall 6.0.1, reboot normally and then reloaded 5.0.594.

Are there parts of the behavior shield in 6.0.1 that installs, even if you custom install without the option?