I recently reconfigured a computer with XP, and, through my own actions, I inadvertently became infected. I installed AVAST!; it didn't find this virus. I installed SUPERANTISPYWARE; it didn't find this virus. I installed SPYBOT; it didn't find this virus. I installed AVG; it found this virus. Now, it I had installed only one anti-virus program, I would have been infected with this one, and likely many more, viruses. Each anti-virus program finds what it finds, exclusive of the others, with no conflict - any conflict shows up early; when you are installing them. Running only one anti-virus program WILL get you infected, without you even knowing about it. And I have been running more than one anti-virus program for more than 10 years, with each one finding stuff the others didn't. So.... Until my machine freezes totally, or a proven conflict arises, I will continue to use more than just ONE anti-virus program.
But I am in the dark about restricted zones; every anti-virus program I have has no setting for restricted zones.....