My wife works in a school and she reports this on 2 different computers she uses as starting from some update (unsure to what component) within the last 10 days. The "fix" used by the school is to remove firefox, so we lose users over it. If she clicks on a link in her Outlook 2010 email, and firefox is the default system browser, she gets a pop up that says: "General failure. The URL was: [URL here]. An error occurred in sending the command to the application." It is firefox 10.0.2, (esr?) Windows 7 Enterprise and Outlook 2010 it seems identical to this sumo report other than the report is about 3.6. http://support.mozilla.org/en-US/questions/777513?s=outlook&r=4&e=es&as=s . I couldn't find a bugzilla, but I probably missed it.
Did you doublecheck the settings in Windows for the default applications (Browser, Email, Media Player, etc)?
Yep I'm seeing this issue too since the 27.0.1 update.
Version of Outlook is 2007
10 months ago