How Do I Remove Symantic Products When Norton Removal Tool Does Not Work?

Youmay find some useful information on this topic here.  For example, they state that in some cases additional actions such as these are required:

Last but not least, you need to download and run one final file. In some cases, older Symantec files may survive the Symantec Norton removal tool cleanup. To eliminate these files, download the Symantec Norton MSI cleanup file (SYMMSICLEANUP.reg) and save it to your desktop. Double click on the file to run it and click Yes to any security warnings that appear.

*note* If you use the Firefox browser, you will need to download a different file to accomplish this tasks. Firefox users, please download this version of the Symantec Norton MSI Cleanup file (SYMMSICLEANUP.reg). All that's left is one last restart and you should be ready to attempt a reinstall of you new Symantec Norton product. If you continue to experience difficulties, you should contact your local computer service center.