Hi guys, I know the feeling as well. Tried all the drivers, all the different settings without any luck. Eventually, I called out a technician from Dell. He opened up the screen and found that the cable connecting to the web cam was loose. There is no room for movement of the cable, thats why it gets loose and thats why some people are having a problem and some are not. If you can check the physical connection to the web camera. My E6410 web cam now works perfectly.
just go and download dell webcam entral, and all your worries will come to an end
its not a webcam its a sensor for the brightness
its not a webcam all it is is a cut out ready for you too put a webcam in the wire for the webcam is already there depending on what you ordered from dell
i have been thinking for months that its a webcam but as the dell website specs says its optional if you put your finger over the so called webcam windows its actually a sensor for the lcd display brightness hope this helps