other people have reported similar problems. i only experience something like this when moving my mouse via synergy to another computer... thereby 'losing' the key up event. since you are on a single computer, that's not your problem.

make sure you put NUMLOCK also in your do-not-pass

personally, i use the mouse to drive and steer... no keys. i also use a stand alone macro for /follow. i read somewhere somebody reported switching to a simple /follow macro and the run-away problem disappeared.

g'luck and let us know how it goes