I spent weeks resolving a problem with ZA Pro because of have McAfee Virus installed. Since I could not use McAfee I elected to use ZA's virus protection. After installing the ZA's Suite I had the same issues as before with ZA Pro. The culpret was a spyware program called Spyware Dector. The symtom was ZA locking up and would take 20 minutes just to get the control panel displayed. After uninstalling Spyware Dector everything started to function properly.

Operating System:Windows XP Pro
Software Version:7.0
Product Name:ZoneAlarm Internet Security Suite