I recently upgraded to IE8 (Beta) and also Firefox 3.0(Beta) and while there are some GREAT new features in them.  I had a strange problem.  When I would click something from from another application my default browser (Firefox 3.0) would open the site but I would get an error message saying that the site couldn’t be found OR (in the case of clicking a link in a Prism application) several windows including the browser would open the site. Read More Below...

What had happened what that in my updating Firefox the old Firefox 2 was STILL installed and I had opened it.  Since it was using the same profile as Firefox 3 it registered itself as the default browser.  For some reason when I opened Firefox 3 afterward it loaded itself as the default HOWEVER when XP would try and trigger the default and FF3 would open XP was looking for a response from FF2.  Since it didn’t the errors and strange behaviours occured.

Confusing?  yep.  But there is a simple fix.

1. Open IE
2. Set IE as the default browser
3. Close IE
4. Open Firefox 3
5. Set as Default Browser
6. ???
7. Profit!

Yep that simple.  Just remember NOT to open up FF2 afterward.