If you’re an SEO, you’ll be using Firebug. There’s a compatibility problem with firebug in Firefox 3 that results in the error message “firebug not a valid install package -207″ or the error message below:
If you have this compatibility problem, help is at hand. Those wonderful folks at the Firebug working group have created a solution in the latest beta: so, you can upgrade your Firebug to the latest beta and it works with Firefox 3. Phew.
Update 2: A few people mentioned this - don’t worry about the Google Toolbar errors! The install auto-updates during the upgrade.
Update 3: A few readers have asked if this solves the problem with Firebug not working in Ubuntu. The answer: yes! 
