It sounds like you have an electrical short somewhere. It probably has nothing to do with your shifting. It may have to do with going over bumps or the motion the vehicle makes as you shift where a wire could move and ground itself.
It would be difficult to guess at your problem without seeing the vehicle. I would suggest that you have a certified technician diagnose this problem. Try to gather as much information about when it happens to help them find the problem. If they can't see it happen, they will have a hard time fixing it. Good luck.
〉 Answered on Dec 5th, 2007 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines