First Logon on a 802.1x

Hi.
I have made some tests with 802.1x in a wired enviroment and a question
appears.

When I log in windows with a user that already logged before I can logon ok,
but if is a new user (new profile) I cant connect.

How can I fix that? I think 802.1x use the cached profile saved before the
first logon (first I login on a network without the 802.1x applied - a normal
network)

Im using IAS and AD and everythig is ok, only problem is the fisrt logon, I
get the message that my domain was not found (because 802.1x allow the
network access only if authentication is ok)

Thanks
Marcos