Video recording (occasionally) does not work on Symbian

Steps to reproduce:

1. Launch examples/camera
2. Switch to video recording mode by tapping the 'Video' tab
3. Press 'Record'

The following then happens:

1. "Recorded 0 sec" is printed in the bottom left of the screen
2. The viewfinder turns black
3. After a few seconds, a dialog pops up, saying "Failed to prepare camera for video recording"
4. In the log, a message is printed saying 'Camera error: "Camera resources were lost."'
5. When the initial dialog is dismissed it is replaced by one saying "Camera resources were lost"