I sell on ebay, too, and I don't take personal checks either. I have caved in a couple of times, if the person had a good reason and good feedback. (Plus, it wasn't for very much anyway.)
I've also refused personal checks if I had any doubt at all.
However, since you've been burned before, I would stick by my guns and not accept her check. Since your auction clearly states your accepted payment options, then you are under no obligation whatsoever to accept a personal check.
Sometimes, it can get very frustrating; dealing with some people. I've had some tough folks to deal with, so I don't bend my rules very much anymore. You have to look out for your own best interest!
You're the one who has to deal with the consequences, so do whatever you feel is best for you! As a seller, I've found out that this is one area where you really have to put yourself first most of the time.
So, if it's an inconvenience at all or something you're just not wanting to do; then don't do it.