I've been exporting footage using the compressor to create a low quality mpeg4. I make sure to insert the end point (O) to signify where the timeline ends, and yet the exported mpeg4 has an hour of black footage tacked onto the end of the video, leading to extended exporting times and a much larger file.
Although I'm not that willing to accept this as an unavoidable occurrence every time I export a video, I went about the time consuming task of inserting the finished mov onto a new timeline, to enable me to simply cut the end off, but FCP didn't like that one bit and rather than let me have my way, gave me a beach ball to play with. Grrrrrrrrrrrr
If anyone can help me get around this, they'd be promoted to genius in my book.