Facebook Notifications sign-in problem

Hi there,
I have been using the Facebook Notifications App that allows you to check your facebook updates from an icon on the desktop toolbar.

Every couple of weeks when I start my mac, there is a pop-up message asking me to sign in to my facebook account to allow Facebook Notifications to continue working (this is normal). But lately, when this message pops up and I enter my login info, the same box keeps popping up again and again with a blank form i.e. it is not signing in.

Has anyone else experienced this? I've tried uninstalling and re-installing, but the problem persists.

It's a really handy app and I would love to have it work like it should. I'd appreciate your help.