I learnt quite early on that "Uninstalling" a programme rarely does. In fact, IIRC, Firefox actually tells you that configuration files will be left behind unless you specifically ask it not to. Then you get things like antivirus programmes which really dig their tentacles into your operating system. Some of them offer specific removal tools, but I've successfully used Revo to get rid of Norton and Avast, and as you've found, it does what it says on the tin! I'm glad to have been of assistance.
TFP