Harrzack:
Greets!Have built a "soldered-together" version of a stepper motor control project with Arduino and BED. BED was stepping fine on the breadboard, but now on the 'built' version, I have a 27khz (or so) signal showing on one of the coil leads to the motor with no step signal on the STEP pin. The motor does respond erratically to the step commands - and after a step, the oscillations stop - or return at a different frequency.
Completely normal, stop worrying about it, its a chopper drive.
What do you actually mean by "respond erratically"?