Ditto...am having the same problem it seems when I upgraded to Firefox 8...seems that Sling won't work now when I try to watch...can someone from support give us an idea what's the fix? or how long before you get one?? this is a big problem, and considering Firefox is one of the only browsers that you support, it's likely there are a lot of people suffering through this also. Please help FAST!
Works fine in Firefox 8
Install User Agent Switcher add on
Edit User Agents in menu
New User Agent
I put Description: Slingbox Compatible
Then User Agent:
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/531.21.8 (KHTML, like Gecko) Version/4.0.4 Safari/531.21.10
I left the rest to defaults
Make sure you select the user agent.
Then reload and enjoy