I have done several recordings without any problems, then I've now done a few where the sound is distorted, with popping screetching and just horrible sounds, not at all what it is meant to sound like. I thought it was the microphone, so I unchecked the box with the idea of recording my voice afterwards. But the distorted sound still happened, the only things running on my laptop is the game plus FBX. Any ideas to help fix??
Did you have the Game Sound Only option enabled?
If so, it sounds like FBX was unable to correctly detect the correct sound format to use while recording. One reason that that would happen is if recording is started while the 'Initialising...' message is still displayed in the overlay.