Same thing happens to me and on my regular machine too, not the hooping problem. Problems on the bottom are usually caused by upper thread (tension, bad thread,bad needle, etc) and above the fabric it is usually caused by the bobbin threads. I'll be waiting for answers on how to stop it from happening also but I think it just happens sometimes to everyone. Did to me last night with the too thick potholder, thought I killed the machine. Had to cut a hole in the potholder to get it off the machine. Good luck and Happy Thanksgiving!
Debra

There is a serger seam ripper, works great for when this happens. Some times I hate to say it but designs can be over digitized , to many stitches in one area. So if this is happening on the same design I would guess that is the problem.

Yes ,This also has happen to me..

This happened to me also. Reason was designs was too dense in a section and machine ate it. I cut it with my mini manicure scissors then used a seam ripper to tear it off. UGH.Then cleaned the whole bobbin area. I had a new needle so I can't blame it on that.Checked tension, checked bobbin.But since I believe in elves and fairies it might have been them also.!! Ha Ha.

Perhaps it could help to do a basting stitches before beginning the embroidery, what do you think of that?