Q: Playback suddenly running slow

Hi,

I accidentally disconnected my external hard drive from my iMac while editing. I got an error telling me it wasn't disconnected properly, then I was asked to choose my library settings. I couldn't 'cancel' so I said ok (the definitions seemed right but probably were not).

When I exited the program and went back to the desktop, I saw I had a new hard drive on it: "Macintosh HD". That was never there. It also could not be opened.

I reset my computer, and the hard drive was gone, but my external hard drive was nowhere in sight. I finally disconnected it and reconnected it again, it was back.

But upon returning to fcpx, the playback started running very slowly and jumpily, so I can't really see what I'm editing well.

Any ideas what may have happened?

Thanks.