OWA logon requires DOMAIN\username

[tangostar]

I'm having trouble with OWA.
When a user logs on over the internet they have to enter DOMAIN\username as their username.
if they just enter username they fail to login and on the second attempt then login is set to mailserveraddress.com\username

 

[xmsre]

In the internet information service manager, right click on the default web site and then go to the directory security tab. under authentication, make sure you have basic checked and fill in the default domain.

 

[tangostar]

ya already done.
makes no difference.

 

[xmsre]

restart your services.

 

[tangostar]

i've restarted the machine.
nothing.