I have encountered a major problem when trying to make an accelerator, at least sometimes.
For the most part it runs smoothly, no hick-ups at all and can reach to speeds well over 10,000 MPH.
Sometimes however, something strange happens, the speedometer pegs at around 2000 MPH and then the ropes, the log, speedometer and thrusters vanish.
Any ideas why this would be happening? No stupid answers such as “Oh you pressed z a bunch :B”