i-movie 11 Cutaway Transitions Crashing!

When trying to eliminate the gap between two cutaways (using the arrow keys) OR when adding a.5 second video fade to the ends, the clip I am moving goes missing when it finally touches the prior clip (turns black sometimes, or the sound goes missing, or it subsitutes an entirely different bit of footage altogether!). I can't repair this by backing up. Have to throw the cutaway clip away and start over. Then I can no longer butt the two clips together or it keeps happening.

Is something corrupt with the program? If so, how do I get that repaired?