Perhaps you should check the mcafee.com website support.
You can not have more than one active antimalware program. The results will be like what you are experiencing.
You need to uninstall the products as well as run the removal tool to get rid of them
McAfee:
http://service.mcafee.com/FAQDocument.aspx?id=TS101331
http://download.mcafee.com/products/licensed/cust\_support\_patches/MCPR.exe
Norton:
Download and run the Norton Removal Tool to uninstall your Norton product