facebook email address not valid

my mom made a facebook account and we have login problems…?
so we made a facebook account for her. she has a YAHOO account, and i know the account is real (in other words, she uses it every day and it has no reason to be fake like facebook says). when we try to log in with the CORRECT password, it says invalid password. we went to reset password, typed in the security words, and clicked “reset password.” it says something along the lines of this email address is not valid. it says to make sure it’s correct (which i know it is) and to retype it. i do, and it still says incorrect email. so to make a long story short, we have the right password, it won’t let us log in, and it won’t let us reset the password either. we tried making the account a second time, but still nothing. how can i fix this/what should i do?
and sometimes when we log in it says
Account Unavailable
Your account is temporarily unavailable due to site maintenance. It should be available again within a few hours. We apologize for the inconvenience.
why does it say this?
Hello
on this page you get
the solution for your problem!
http://www.facebook.com/help.php?page=749
Internet Tools & Uses : How to Join Friendster