well, i used to have the same problem and resorted to removing and adding the widget just to get it to work. most of the time when i do this, some widgets are automatically removed.
then i found out that this is due to some conflicting widgets on hildon home - which can be solved by not adding certain widgets on the home screen. for me, it's the "TV out control" and the "TVBGone" widget. according to other posts in other threads, this might be caused by other widgets like "Forecaweather" and some others, so do try it out and cheers =)

-Ethan