Symantec's antivirus software not only slows system (McAfee too), under certain conditions (ie. expired, firewall, blocking useful programs for no reason), it could be the cause of some other program not running properly, even after its removal.
At one client, after uninstalling a client's Norton (I think it was halfway uninstalled...or halfway shutting down after restart request), since there's a lot of stalling (more than 30 minutes) during the uninstallation/restart process, I believe I force shut down during the Shutting Down... screen, out of impatience.
Then, I noticed the newly installed ACT! 2008 couldn't access a certain network database (anymore? - not sure if I tried it before Norton uninstallation). Not knowing Norton could still be the culprit after its removal, I tried all kinds of methods I could think of...from uninstalling ACT! 2008 to changing windows user account to firewall settings to everything other small tricks I could think of.
After a couple of days, I finally solved it this morning with one last solution I carried with me since I woke up.
I remembered Norton has provided a special Removal tool to remove all Norton products once and for all. I was half sure that the ACT! problem may have something to do with the already removed norton, but I didn't want to believe the first uninstallation attempt wasn't complete and that Norton's Removal Tool would do any better.
But after downloading the removal tool from the official site and running the process, ACT! 2008 worked like a charm. Problem Solved.