You may download & run the Norton Removal Tool to remove Norton completely from your machine & check if the issue persists.
Download and run the Norton Removal Tool to uninstall your Norton product
You may also configure the computer in clean boot and check if the issue persists. It will start Windows XP by using a minimal set of drivers and startup programs and helps to eliminate software conflicts.
The following link has steps showing how to perform clean boot: http://support.microsoft.com/kb/310353