The other problem I would have is it would say the the video clip was corrupted and would have a yellow "!" over it - when it wasn't. This drove me crazy for about two weeks trying to read up on what the problem was. End result was either you have to have a plain video with no transitions, not small clip sections, no music, etc. - or if you want all that fancy stuff then you need to create small video clips.
Example - our movie of our trip to Copper Mountain. I split the sections up to us at the Airport, on the plane, take off, landing, etc. and created one movie part 1 and published it. Then part 2 was the video of the resort, our room, the eateries - us walking around, etc. That was part 2. Then I created a video of our first day snowboarding as part 3. Another video of the 2nd day boarding. Another video of our 3rd day boarding. Then the last video of us leaving, etc. I named all these videos and published them, etc. If you are adding music that is another problem why things can freeze. When I had all the sections created then I started a new movie and brought the published videos in and then added my title and credits and then published it and no longer had the problem of it freezing.
Again, it is all the transitions, and captions, music, etc. that will cause it to freeze if you try to do it as one whole 10 minute video. Believe me - I spent two full weeks trying everything and this is the conclusion I came up with after reading for help on the internet.
I learned to snowboard at 50! woo hoo!