hm
Hi,
did you activate the option "vhost security"? Another chance to fix this is, if you logon to plesk than you can choose the domain. If you check the domain above the list is the option "chexk permission" if you choose this you must deactivate the first check box and than confirm it. After a short time the check is over and you get a report to the Mailadress you gave the system. If this also does not work you can try to setup the domain new in iis by using cd %plesk_bin% and than try websrvmng.exe --remove-vhost --vhost-name=domain and than websrvmng.exe --reconfigure-vhost --vhost-name=domain
Hope this can help you,
dkuwi