Your max feed rate is probbly to high. once they get out of the accleration curve phase the steppers are trying to move to fast
try a contolled move eg G1 X10 f300, ie move to X10 at feedrate 300. This should move any distance, but slowly.
If you take a look at the top of pronterface there is a section x/y mm/min, this is the max speeds for manual moves in the X and Y direction. lower that till it works, then set your max fead rate to those numbers. then gcode cant move faster than your hardware limitations
try a contolled move eg G1 X10 f300, ie move to X10 at feedrate 300. This should move any distance, but slowly.
If you take a look at the top of pronterface there is a section x/y mm/min, this is the max speeds for manual moves in the X and Y direction. lower that till it works, then set your max fead rate to those numbers. then gcode cant move faster than your hardware limitations