2.1.25, with new patch, set on "high" now does work with 2000SP1. However grc.com now shows POP3(e-mail) port "open". (worst possible) Shows "stealth" (best) w/o patch or SP1. May be due to Antivirus e-mail scanner, not patch, however. (I use PC-Cillin 2000.) Even if it's no longer 2000 or Zone Labs' direct problem, anyone running TM is not as secure using SP1 as w/o SP1.