help - registered user isn't showing and can't get on

she has registered and got the welcome back in her mailbox. I can't see her or her email addy, in admin. I cant register her with a different name as it says shes already got her email in use. she cant get on with her username...

Any ideas?

shes given me her username and password...

I can't (as admin) see her anywhere, she is not showing as a new registered user................... but when I try to register her, using her details, it says username already taken and email address is...

So why can't she get on,
Why cant i see her as a registered user

any one?