I just started Android Studio and I got this:
WARN - .project.GradleProjectImporter -
2014-03-26 13:58:00,447 [ 21456] INFO - .project.GradleProjectImporter -
Unable to load class 'com.android.builder.testing.api.DeviceProvider'.
Functionality like editing and debugging won't work.
I updated Android Studio and I got a different problem when starting, but it fixed itself.