I have the same problem. I reported the problem to Facebook and got the following reply:-
"Thank you for submitting this bug report and the taking time to help us improve Facebook. Unfortunately, we are unable to respond to every bug report individually, but we are reading them.
For more information about issues currently affecting the site, please visit the Facebook Known Issues Page. We appreciate your patience and feedback as we work to improve your Facebook experience.
The Facebook Team"
Not very useful I'm afraid! Hope a fix is sorted soon, it's an annoying problem!