Well, now that Firefox 3.5 is everywhere, addon developers should seriously consider upgrading their addons for compatibility. Just the day I installed the latest release, half of my SEO addons were not working!

Here is a work-around to get your addons working by disabling the addon compatibility check. This support is not present out of the box. You need to add 2 keys. The steps involved in doing this are :

1. Type in about:config. Agree to anything it says.
2. You get a list of configuration values. Right click on any one and select “New->Boolean”, the last option.
   

   New Firefox Key

3. Next,you get a window asking for a name for the key. Enter the name as “extensions.checkCompatibility”.
   Set it’s value to false.
   

   New Key

4. Again create a new key, with the name “extensions.checkUpdateSecurity”.
   Set it’s value to false as well.
5. Restart firefox.

This tweak might create some problems for your browser like, it disabled my address bar and the search bar. I easily got them back from View->Toolbars->Customize and then dragging and dropping the desired items.