Try it now, Sheila. I erased the url from your sig, but I also filled in the 'flyby registration' field with a generic 'LNC fan'.
This field is required. If it's left blank, any changes to your profile won't take. (It's blank in your profile, of course, because it's a field that was added after you joined the forum, so you never had the opportunity to fill it in.) Although, usually, it simply doesn't make them. I've not seen it throw up the error message you got.
But filling it in seemed to do the trick, so...
LabRat