White thread keeps pulling through

Question

When i am doing some automatic embriodery the white bobbin thread will pull large amounts through the the front of the fabric being stitched, resulting in a ruined design. I have lost the mannual unfortunatly as the machine was second hand when i got it. It has only been recently that the white thread has been coming through. The Machine sews fine when not using a memory card. Please help me!Thankstpjones