Skype - Unable to use Webcam

Apparently Asus motherboards have a utility called Ai Charger+ that causes this issue, and there is a semi-official patch to fix the problem posted by ASUS moderators on their forum:

http://vip.asus.com/forum/view.aspx?SLanguage=en-us&id=20130624030331031

Found this via:

http://forums.logitech.com/t5/Webcams/Quickcam-Pro-9000-ASUS-Z87/td-p/1054139

You stated that the cam works in a VM. I assume that VM is hosted on the same machine that has the issue? Does the VM run the same OS as the problematic PC? If so, does the webcam stay in the same USB port when you forward it through to the VM where it works fine?

Just reading through your very detailed (thank you!) description, it would seem to be a very strange issue indeed. I would be interested to know if another webcam that is known to work, behaves in the same way on that pc. If it does, perhaps it's something to do with the actual USB drivers? The HID stuff. You might try downloading the latest chipset drivers for your mobo, then uninstalling and deleting the existing USB/HID drivers and then reinstalling the chipset drivers and see what effect that has.