That is a question to ask Google about their product, the Google Toolbar. Google needs to update the Google Toolbar program for Firefox 5.0.

The Google Toolbar 7.1.20110512W version does work pretty good in Firefox 5.0 by using the Compatibility Reporter extension. But not every feature works 100% and needs to be fixed.
https://addons.mozilla.org/en-US/firefox/addon/add-on-compatibility-reporter/

http://googlesystem.blogspot.com/2011/06/enable-google-toolbar-in-firefox-5.html

As a simple end-user, this is unacceptable! Google is blaming Firefox and Firefox is blaming Google! Nobody is owning up to the problem. They both screwed up. If Firefox wants to keep me using Firefox, then this needs to be fixed sooner rather than later. As much as I don't like IE, at least it hasn't blown away my stuff if I make an upgrade.

Included with every Firefox extension is a file named install.rdf. In that file is a parameter "em:maxVersion" which indicates the maximum Firefox version with which the extension has been tested and approved by the developer (Google, in this case). Only the developer (Google) is responsible for changing that parameter. Firefox enforces that parameter.

That said. Google and all other developers know where to find the Firefox release schedule for new versions and where to find the test versions (beta) to use to test their product. The location of the release schedule and the beta versions is no secret. Firefox 5, and all other versions, underwent several weeks of beta testing, during which third-party developers (Google) had an opportunity to do their testing and make necessary changes to make their product(s) compatible. In addition to the 4 weeks of beta testing for Firefox 5, Google has had an additional 19 days since the release of Firefox 5, to make their product compatible. Ask Google what is keeping a compatible release from being introduced.

I tried to ask google but I was only able to make a comment. I agree with wbt - they are blaming each other. I do not want to mess with files and whatnot so I just went back to Firefox 3 until this is sorted.

Thanks for the feedback everyone!

"I lost all of my bookmarks when I updated..."

Create a shortcut for google bookmarks and drag it to Firefox Bookmarks bar.