When this happened to me it meant the bobbin thread was not threaded properly. It happened when I would pull the thread thru the cutter before closing the bobbin cover. My machine is a Husqvarna.
Oh, and I cannot use "bobbin" thread in the bobbin for embroidery - there is a bobbin embroidery thread but I have not tried it yet. I just use the white embroidery thread.
Good luck.
Last edited by quiltingcandy; 04-02-2014 at 12:55 PM.