Cause:
Acceleration manager not installed on Windows.
Solution:
Install and configure the Intel Hardware Accelerated Execution Manager through
the SDK. Complete instructions on the Android site. [Video].
Cause: ?
Solution:
Either restart the emulator or restart the logging service.
Cause: ?
Solution:
Deactivated the checkbox "Use Host GPU" within the settings of the virtual device.
Cause:
The STUDIO_JDK environment variable doesn't point to a valid JDK.
Solution:(Courtesy of Alex)
Download Java from the Apple website.