Now, do you want to know the whole story on how I knew this???? After first getting mine after the 6600P just came out, I got the same error message and in a panick I drove all the way (45min. drive) over to the shop where I purchased it just to find out that all I needed to do was re-thread it! Was my face red!! Good excuse for going to the quilt shop I guess, huh? I'm so glad that someone else could learn from my red face moment....pay it forward!