Norton security scan

Norton security scan was downloaded unwantedly with another software, and apparently it downloaded incorrectly.  No matter what I do, disable, remove, anything even in safe mode;  an error message appears saying the action is void because a 'scan is in  progress' . No norton removal tool helps.  Is there anything I can do other than a clean erase and reinstall of Windows 7?   This has been extremely fustrating, because my laptop constantly locks and is unbearably slow.  It wont even shut down for at least 20 minutes.   Please help.