this is most likely your car docking sled sliding out.. I had the same problem because I had no locking do-hingy (DIN mounting cage I think?) to lock it into the dash. My solution was stick a penny into the dash so the lower part is in the dash and the upper part is keeping the docking sled from sliding out. Another solution could be cable ties to tie the back of the docking sled into something in your dash. Be creative.