Other applications might have crashed or not released the camera. ... Yahoo! Messenger is using the incorrect camera device.

Messenger for Mac, including the following: ... Application freezing or crashing

This article will describe how to troubleshoot:

If you have archiving enabled, you can retrieve your Yahoo! Messenger conversation history from Yahoo! Mail. While it is not possible to directly download your conversatio...

Information on how to get help with Messenger Voice or Video connection drop outs and how to fix Voice or Video connection problems.

To optimize compatibility with Yahoo! Messenger , please check for software updates for your Mac. Here's how:

It's not possible to be signed into Yahoo! Messenger in two locations simultaneously on the same computer. This includes the integrated Yahoo!

Double-click the Yahoo! Messenger icon on your desktop or in your icon dock.

If you'd like to chat in Yahoo! Messenger using one of your account's aliases instead of your main Yahoo! ID, enter your alias into the Yahoo!

Select Messenger Select Sign Out Click Yes