Yeah I agree with Mac. To solve this (in Windows 8) go to Control Panel - Hardware and Sound - Manage Audio Devices - highlight the default device and select Properties.

Then select Advanced and disable (uncheck the two radio boxes) that say:

Allow Applications to take exclusive control of this device
Give exclusive mode applications priority

This will then unlock the device to be used wherever and whenever. It is also a good idea to repeat the process on the Recording tab as well.