I was on a 7 week plateau this summer. It was very frustrating. I had to add a lot more activity to get off the plateau, even though I was following the weightwatchers program pretty faithfully and on the lowest number of points you are allowed. I think GLC's suggestions about changing what you eat can be helpful, and changing the kind of activity as well might be helpful.

I have read some things that say your body starts to think it's starving and slows down the metabolism, so sometimes you need to eat more ... though I have a hard time actually following that myself.

Good luck