iSight wont work

When i click on photobooth i get a message saying "photobooth can not open because the camera is in use with another application", and when trying to record video with iMovie it says no camera attached even though the iSight camera is selected.

I have searched and i can see no other application that would be using the iSight. I recently did a re-install of OSX and the camera worked fine before.

Has anyone got any ideas???

NB: its ok all done just installed an update and its working now