A browser update certainly makes browsing a safer task but, you may have to loose your favorite add-ons if they are not compatible with the latest release.

Here is a trick to get them back to work, which will help you greatly as you upgrade to Firefox 3.5 (b99) :
- Open about:config. To open it simple type about:config in the address bar.
- Accept the warranty condition.

- Create a new boolean entry. To create, make a right click anywhere and select New > Boolean.

- Name this entry as : extensions.checkCompatibility and set it to false.
And, you are done! Now, add-ons will work irrespective of their compatibility with the version of Firefox.
This trick is very useful for Firefox beta users. :)
Thanks How To Geek
PS – Changing Firefox settings may cause trouble! Try it on your own risk.
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Thank you… it worked very well with my plug-ins !! :-)
use this:
https://addons.mozilla.org/en-US/firefox/addon/6543
much safer