Last night I was running my Practicalcnc router(steppers)

I was routing plastic, the roughing went o.k, (all linear paths) but when I was running the finish program the x axis was definitely losing steps after a bit.
The finish path was for a u-shaped part so the x would completely stop as the z fed vertical on both ends. I noticed that when the x would stat again there was a definite jerk into motion.
I dropped my accel way down to 50 to see if it was an accel problem. No difference?!

I tried the smothing (G09 S5, G09 S3) again no difference.

I check mechanical and didn't find anything.

I originally was running the file from a USB drive. I copied the file to the hard disc. re-booted and tried running from the HD. Still no Joy.

HELP please.

Regards,
Cutmore