From what you say, it seems Flashgot is at the heart of your situation. Whether you download a virus or flashgot messed up, or Norton interfered with the download, there is no way for us to know for sure.
Files may not delete because something is using them, although Safe Mode should have helped, if it is some type of utility it may still be running.
I would probably look at Task Manager to see if something is running that looks a little strange and shut it down. You may stumble on the problem item. And use MSconfig.exe to keep it from restarting on boot. If it is an errant utility, the CPU utilization might give you a clue.
If you still cannot delete the file or have not been able to delete if from the other account, you might boot to the recovery CD or Install DVD and use the Repair options to open a command prompt. You might be able to delete the file from there.
As Captain Jack says, staying with the new profile might be best, but if you do have a virus, I would be a little worried.