Norton Re-installation Query and Scanning Error

I've just recently renewed my subscription to Norton, but I've encountered a problem with the program. When I click 'full scan' or 'custom scan' nothing happens, despite what my computer's task mananger may assure me. I've been having this problem for a few weeks now meaning I am unable to scan my computer. I think re-installing my Nortan program may help, but I'm afraid that I won't be able to reinstall my anti-virus and keep the subscription since I've already registered it. If anything I may not even have to re-install my Norton Internet Security but I havn't yet found any solutions. Can someone please help me find a solution?