The bobbin thread is catching on something. Make sure when you load it, that it's feeding in the right direction and pull it up before you start and hold it for the first few stitches.

Are you sure that you have the thread coming off the bobbin in the right direction. This is a little detail that does make a difference. Also, when was the last time you cleaned out the bobbin area and took off the feeddog cover and cleaned out the feed dogs. Lint build-up in these areas can cause all kinds of problems. I hope that you are able to solve the problem with these solutions. Otherwise, I think you put a burr in the bobbin area when your needle went wonky and that the bobbin thread is catching on the burr.

Annie

Thank you - the problem seems to be worked out.. I think my material was to thick/dense for my needle...