Ok, last week, i replace my usb control card, because it went bad. Shop bot is back up and going... but ever 3 minutes, it jerks and stutters (all 3 axis).... Ill close out the SB program, open it... works fine for 3 min.

Ive changed usb cords, computers etc....

It may be worth noting, I have upgraded to the newest software before i replace the usb control card, just as a diagnostic step. Any help much appreciated