Hello 
I'm currently quite desperate. I don't know when my issue actually started, but not more than a week.
The first issue : My integrated webcam seems to have problems. I used "Alien Autopsy" on my laptop and all tests were OK (I could see myself, the little LED light was on), so I assume it's not a hardware issue here. But the webcam can't be used by any program. Dell Webcam Central can't use it, nor can Aliensense and Skype. It's just black, and the LED near the webcam stays off. I tried about... Everything I saw on the Internet. Fn + F9, disable/enable again the webcam, disable facap, uninstall the integrated webcam's driver and install it again... I even tried a System Restore before the latest Windows Update (03/12/2014). But nothing works.
Second issue, which might be linked to the first : I tried to install two other webcams I have (external, using USB ports), and even with the installation complete without error, no image is displayed. The webcam seems to be off. I tried them on other laptops and they work fine. I tried to change the USB port they were plugged on, no change.
Does anybody know where it could come from ? I'm starting to wonder why every "image capture" devices seem to not work.
Thank you for any contribution.