I was kicking myself for being an idiot but I now know that many people have made this same mistake. When I installed prop guards I used the longer screws that came with the guards to attach them to the copter. The other day I decided to fly without the prop guards and after removing them I reinserted the longer screws. Big mistake! The longer screws went up into the motors and ruined the windings. I have now ordered new motors (say goodbye to $100). Hopefully I will be airborn again in ten days or so. Note: If you remove the prop guards, use the original short screws that came with the phantom to secure the motors. Hopefully, this will help someone avoid a costly mistake.