craftgrrl | A desperate cry for help. (Reply)

I know asking questions that have already been answered is damn damn damn irritating, but I checked memories (and a few troubleshooting websites) and nothing's been suggested I haven't already tried. Jesus Christ, I'm ready to smash my sewing machine into tiny pieces.

I'm trying to hem a skirt. I had some trouble with the thread doing that weird loopy thing, but I re-threaded and it fixed itself.
I start a seam, all's going well. It starts to feel slightly odd, so I stop and halfway down the thread's gone all loopy again.
I've re-threaded the machine about ten times, adjusted the tension, cleaned all over the place, and still it's happening. The top thread and bobbin thread are the same weight, btw.
Any suggestions?

Also, in the memories someone said this could be due to the bobbin being the wrong size- I had the problem fixed and it started again, could it still be down to the size of the bobbin?