These problems happens because when you install Windows XP Service Pack 3 or Windows Vista SP 1, a tool that is called Fixccs.exe adds numerous registry keys in many locations (some of them within the Symantec registry keys) but is unable to remove them.
If you experience any such problems after upgrading your Windows operating system download and run the Symantec Registry Repair tool. No installation is required. It will automatically remove any such entries. (more info)