Just make sure you've done a clean deinstall of ZAP. (The key to a clean deinstall is making sure ZA is shutdown before running the deinstall procedure.) Also, reboot, of course. Details on removal from Zone Labs: http://www.zonelabs.com/store/content/support/zapInstallFAQ.jsp#1install
Be sure to follow these instructions: http://www.agnitum.com/forum/showthread.php?s=&threadid=4353 It was found that the ZA instructions are not always enough. btw: good move