This is usually caused by two applications trying to stream video at the same time. To solve this, do the following:
Please read the message that is being presented at the bottom of the screen, this message will provide with the name of the other application that is using the camera, terminate or close the other application to start using the Quick Capture software again.
In other scenarios you might get a “Webcam in use” error message whey trying to use an application such as Skype, AIM, Yahoo, etc. To address this issue please close the LWS software.
Check your computer documentation to see if you have a device such as a TV capture card that might be streaming video. If so, disable these devices and check your chat client again.
You should now be able to stream video chat without receiving the "Webcam in use" error message.
If the above solutions do not resolve your problem, consult Knowledge Base article 17009 for instructions on contacting Logitech Technical Support.