I posted this a few months ago but the video may be relevant.
PS: I was not trying to sound arrogant or cocky about @jnordyke Johns issues. I truly want to help with this issue. I just spent 2 carves a month ago fighting this exact thing… long stringy wisps of wood that would wrap around the router and clog up my exhaust ports. It was frustrating until I figured it out. I would also mention that too small a stepover can cause the same thing if you push that setting too far.