did you change to 64-bit?
I am on version 43 and Help->About Firefox neglects to say which version it is. My concern is that suddenly Adobe Acrobat and Slingplayer are "incompatible" and you are blocking me from getting to Slingbox.com to see if they have any solutions.
hi zerosumgame, no you are still using regular win 32bit firefox (as no users were changed to a different version during an automatic update).#
the issue you see might be due to the new addon signing requirements that have been introduced in firefox 43. please get in contact with the addons' vendors to inquire how they'll make available a verified version of their addon in firefox (which is required in current versions of firefox and has been communicated to developers for months - so they had enough time to prepare).
There is still the issue with Slingbox you did not address seeing that they insist on installing the player you are blocking before I can contact them. this new "feature" needs to have a way to suppress it.
See if this helps you to get Slingbox working.
Override add-on signing (advanced users): You can override this setting by changing the xpinstall.signatures.required preference to false in the Firefox Configuration Editor (about:config typed in the URL bar). Support is not available for any changes made with the Configuration Editor so please do this at your own risk.
Note: That pref will be gone in Firefox 44 (Release slated for Jan 26. 2016) so user's of currently un-signed extensions should contact the developers of those extensions and prod them into getting their act together & get their extensions signed by Mozilla. Otherwise the users of those extensions will be SOL come the release of Firefox 44. Mozilla has already pushed back the version in which this new security feature was to be enabled from Firefox 40 to 44. I doubt if there will be any further reprieve.