Hello Mike :smileyhappy:

I think you need to run the Windows Installer Cleanup Utility

Read the instructions here before using it.  There is a download link too
http://support.microsoft.com/default.aspx?kbid=290301

You will see a list of all installed programs.  Just remove the Sonic entry.

If you use this utility to remove the Windows Installer configuration information for Sonic and you plan to reinstall the program, you should reinstall the program in the same folder where you originally installed it. This prevents duplication of files on your hard disk or disks.