A couple of suggestions that I have not yet seen on this thread which apply to most any case where one app is misbehaving:
Go to Settings->Applications->Application Manager, find Facebook, Force Stop and then Clear Cache. Back out , and see if the problem is still happening.
If that doesn't work, you can go to the same place as above and Force Stop and then Clear Data. Note that if you do this you will have to login to Facebook and reenter all of your Facebook settings just as if you were running the app for the first time.
And in both of the above cases all of your Facebook feed to be displayed must be re-downloadad so if you are concerned about the amount of data being downloaded it is best to do this while on WiFi.
Larry