My only solution right now is to simply not have her do the work on her own. I stand at the whiteboard and write the questions out and have her feed me the solutions step-by-step. As I write, she does too and we seem to get through it fairly quickly and enjoy our time. But I don't know if this will help her focus when she needs to do independent work.
Luke, Gary et all responded with the fantastic advice that if that works, then go with it.
I'm happy to report that math, using the whiteboard, has blossomed. Freed from having to work through worksheets on her own Catherine now zips through new concepts and works with speed and ease. Her mental math is improving and her general attitude towards math is getting better as well.
Thank you, thank you, thank you.