The only way I found to fix the 8.0.020 upgrade or clean install issues of PC's going slow etc was to uninstall and re-install the last version. Spent 5 hours trying to install!
reason for slowness is a permissions issue in the registry which cause the truevector service to be unaable to locate vsmon.exe and other files, and then the truevector service starts up and stops and restarts every 5 seconds and makes your pc so sloooow!
To install you may have to disable the truevector service whilst you de-install the v8.0.020 version (In the services panel)
Guru, please can you make the last working version available on the zonealarm web so that people can get back up and running whilst this issue is sorted out?