When you enter the setting ID (e.g. network.proxy.type) and value in the drop down dialog, just tick the box that says 'lock setting' underneath.
cheers
Matt
Thanks! Awesome, now I see that option.
When I set the network.proxy.type value and tick the 'lock setting' it does change the setting in Firefox but it doesn't seem to be locking the setting. I can still go to the Firefox prefs and manually change the proxy settings. Is there something else that I'm missing?
I figured it out. It's because I was testing on the same computer I was setting it all up on. Once I disabled the CCK Wizard the preferences were locked out. Moral of the story, test on a different computer! Thanks for your help.