A serious warning.
I've been using Firefox for over 4 years and like it a lot. Periodically it offers to update itself. I've always said yes. I was up to version 3.6 and this morning it gave me the option to move to the newly released version 4.0. "Sure," I figured. "Why not."
I'll tell you why. I clicked the upgrade button, and my computer chugged along. Thirty seconds later Firefox 4.0 was installed. Then I got a box telling me that it was checking the compatibility of my browser add-ons. Surprise! Three out of the four weren't compatible.
Assholes. It would have been nice to know that before I ran the upgrade. I had no strong urge to be the first on my block to run the new version. I would have waited until there were 4.0 compatible versions of my add-ons.
While 4.0 has been in beta testing for months and months it was just finalized yesterday. Mozilla is pushing it like mad. There's a link on their site which offers to let you install 3.6, the previous version. Surprise again! The only thing you can download is 4.0.
I had to go to a 3rd party site to download a previous version that works with my add-ons. It took around half an hour before I got things fixed.
If you're a Firefox user I suggest that you visit the websites of the publishers of each of your add-ons to see if they're compatible with 4.0 before you upgrade. Eventually they'll release compatible versions but there's no pressing need to upgrade before they do.
I think this will let your add-ons and extensions work with 4.0