I was editing in FCX, draggings clips around on the timeline, when suddenly the interface started getting sluggish.
Specifically, the audio is lagging behind the video. I hit play, after a brief pause the video starts playing with no audio, then a few seconds later the audio kicks in, but a few seconds behind the video. The original file is good. I pulled out a backup copy of the media and the project from before the invisible cataclysmic event (whatever it was), so I replaced the event and the project... problem is still there.
Files play fine in quicktime.
Here's an odd thing... the volume icon on my MBP is greyed out.
Starting anyone run into this... I'm going to google.
I'm calling it FCX. They took the "pro" out, so I will too.
I'll reconsider after the first upgrade.