Problems with invalid user name and password

Question

We have a one week old MacBook 2.2GHz basic white model that is generally working well.
However a problem has now arisen whereby on any attempt to shutdown or restart it won't accept the administrator user name and password, returning an 'invalid' warning. The issue seems to be the user name as the administrator password has worked OK in other situations. Naturally I have checked and re-checked the user name (which was in the form (first name followed by surname in upper and lower case) and it was OK (in any case it was being prompted automatically by the system.)
I have subsequently changed the administrator name (to the form first name only in upper and lower) and the password as suggested by the following article:
http://docs.info.apple.com/article.html?artnum=306876
Nothing has changed. Can anyone help?

Answer 1

HI Martin, a late post to confirm the solution from the last post by using the "RETURN" key works..
(mouse click worked ok in Tiger 10.4.x I thought).
Tis was a delight and so obvious after seeing these symptoms.
I have posted this entry in case anyone else get's into this situation since OSX LEopard 10.5. Several people have encountered this issue where they may have:
• LEopard 10.5.x installed
• have 2 or more active users LOGGED into the OSX system via fast user / fastuser switching
• request a SHUTDOWN or RESTART from an user
• get a OSX request to supply administrator attributed user and it's associated password to validate SHUTDOWN | RESTART request,
• have admin | root account verification failure of password after 'clicking'.
After some months of frustration, it seems a simple PRESS of the "RETURN key" works!
Simply, DON'T mouse click after entering admin user/password.... instead press "RETURN" key.
fwiw.
w