Hi,

You really should not need to press "Edit" to edit a video if you are in the the main screen.  Does the screen look something like this, and what part is going black, is it the whole computer screen or just the playback monitor.  In this screen shot, the video monitor is black because the playback cursor (the orange vertical line) is not over a video object.

If you could provide a little more detail and perhaps a screen shot it would help a lot in finding a solution to this problem.

Good Luck