Camera APIs may use/report incorrect supported resolution on some Lumia devices (Known Issue)
The camera APIs on some Lumia devices return an unsupported resolution value and set this to the default value. This issue may also affect other manufacturer devices, but that is untested.
In affected Lumia devices the camera APIs will return an unsupported resolution value ("1280x960") in the set of resolutions the front camera is expected to support. The incorrect value is also set as the default resolution, so that if a developer does not explicitly set the targeted resolution (or sets it to this unsupported value) the camera will freeze and will only recover if the phone is rebooted.
The issue is known to affect the Nokia Lumia devices which have a non-HD front camera: RM-824, RM-825, RM-826. It is caused by a bug in the camera's configuration.
When using the front camera you must set the desired capture resolution explicitly, ensuring that you do not use the high resolution value returned by the API.
You can use DeviceExtendedProperties.GetValue("DeviceName") or DeviceStatus.DeviceName() (if targeting only WP8 devices) to query on which device the application is running, and if the returned string contains one of the RM codes mentioned above, clean-up the list of supported resolutions and set the capture resolution to the supported value of 640x480.
The issue affects only the specified devices and is expected to be fixed in a subsequent firmware update.