error after update 8.1 -> 9.0.1

[chileno]

Hi Guys,
I have a very serious problem, when update my plesk from 8.1 to 9.0.1 in a windows2003 box all ok, but when I run the link: http://localhost:8443 then the following error.

ERROR: Exception
The system cannot find the file specified. (Error code 2) at Unable to connect to pipe \\.\pipe\psapipe

0: plib\constants.php3:62
get_admin_password()
1: plib\constants.php3:62
require_once(string 'C:\Program Files\SWsoft\Plesk\admin\plib\constants.php3')
2: auto_prepend\auth.php3:46


any idea? any fix?

thanks!
alejandro gajardo