Your fatal error was probably using Norton in the first place. Anyway, go into the registry (run > open: regedit) and remove all keys relating to Symantec or Norton (I'm assuming you don't have any other software from Symantec installed). Restart the machine and then you should be able to install Trend Micro, which is good stuff. Just remember, don't install a new antivirus without removing the old one first. They don't play well together.
i did wat u said and it still says fatal error during uninstallation>?!!!