Can’t delete file using “File Assasisn”. What now?

I have a file thats got a hold on my system. I came to Tech Republic and downloaded “Free File” The program froze when I entered the the file to be freed. I then downloaded “File Assassin”. When I go through the process and enter the file, my system goes completely with a blank screen. I disconnect the plug and reboot. The system comes back with the file Still there and not deleted. Antivirus is norton 2007. No viruses. Help!!!!!!!!