I've been having the same problem but its very intermitent, all ive been doing is rebooting which seems to temporarily solve it, but would like to find a real fix.
I wasn't sure if it was down to OC, modified hildon, or theme customiser, or any number of other devel apps.
I'm hoping that the CON900 app will sort it out by restarting processes without needing to reboot.
But really i think the best thng would be to find the actual cause.