Basically if you have the tweak called iOS 6 Photos Menu or FacebookThis then uninstall them and you might have to use an app like iWipeCache or fsWipeCache to clear your cache.
I am having an issue with mine as well. The problem only shows up in landscape mode. I looked through the linked threads but no solution in there for me.
Still having this issue, TBH though i am not sure i ever called up the multitasking background while in landscape mode before the JB. Im sure i did, but just can not remember.