This happens to me when I put the bobbin in the bobbin case unwinding the wrong way. The unwiding has to be threaded in the crooked S shape. This is for most machines that have a vertical bobbin and critical for the older Singer machines.

I don't know what kind of machine you are using, but mine will do that occasionally (janome 6600) and all I have to do is shut it off, and then turn it back on. Somehow it's electronic brain gets confused....am guessing it's been around me too long....LOL

That happened to me last night. Top thread got hung up and broke. I decided the needle also needed to be replaced and I put it in the wrong way. I got a mirror to see how it should go and I had it wrong. Caused skipping stitches. This was a vintage machine.

When this needle broke, skipped stitches, I changed the needle, cleaned everything, re-threaded, etc., etc. & it still skipped stitches, I finally tried a different size needle (was using 70/10 & changed to 90/14) & that fixed my problem.
Marilyn

Yournfirst needle would have been for very fine fabrics and sounds like you were sewing with heavier needing a stronger needle. Anyway, since I have been sewing jeans purses, I broke a couple of 90/14 needles, so got wise and bought some jeans 110/18 Singer brand( I have a Brother) and no problems since.I just have to remember to change needles when on a part of the bag that is NOT denim!

DogHouseMom...I like your saying "When you really want to slap someone, do it and say "mosquito!".

When this happened to me, I removed the broken piece of needle, then noticed the bobbin still had some issues. I took the bobbin out, and on the side of the bobbin case, there is a small screw. I tightened that screw just a little bit, and fixed the bobbin problem.

Well I have a Babylock Quest, and it has a thread carrier arm right above the spools of thread that folds down. If I forget to put that arm back up it will do what you are experiencing. So if you have one of those arms don't forget to put it back up.

Make sure the thread coming off the spool hasn't gotten itself wrapped around the spool pin under the spool.

These machines have so many "quirks" and are so sensitive to precision things. I think it is built in just to vex us. It is so easy to miss a step in threading and that messes everything up. Last night my machine was making a very small "popping" sound. I realized that I can't remember the last time I changed my needle (just lazy). The sound is gone. I think the point on the old needle was flat instead of pointy!
Sue