IPS & Toolbar in Firefox keeps being re-enabled

I do not wish to have Norton IPS 1.0 & Norton Toolbar 3.7.2 enabled in Firefox 3.6 so I have disabled both of them.

Why does Norton keep re-enabling them at each re-boot?

Please tell me how to stop Norton doing this without having to disable each one and re-start Firefox at each boot up.

If any Firefox Add-on is disabled then that is how it should stay!