sounds like yah u either have a virus or some conflicting software, another firewall/AV prg running, do u run windows defender? try doing a clean boot with just symantec services/startup items running (msconfig). also you should have a symantec folder in my docs and there should be a TXT file in there that should have your pro key, or try scanning the reg for Kstore folder ( Me thinks it is in HKLM\software\symantec) the Kstore key should hold your pro key..... if you tried all that sounds like you product maybe corrupt, and you may need to reinstall. you can try running some programs from symantec (not sure if they will work with your ver though, cuz it sounds like you are using a corporate edition) go to
www.symantec.com/autotools, or
www.symantec.com/cstools