403 error says me that you have some issues with configuration of IIS
I do not now how to handle such type of issues, probably you need to contact Parallels Support Team, provide them credentials and they will help you.
ISince you get the error only in case 1 then I assume that something is wrong with _default_ page of _default_ Plesk site. Maybe there are notenough permissions...
It would appear the default document at C:\Program Files (x86)\Parallels\Plesk\admin\htdocs has been deleted. If you have the file please send here.
i can check then..
Please post the all the files inside the %plesk_dir%\admin\htdocs for Plesk 11.0.9 installed on Windows 2008 Std x86 .. index.php and login.php3 are missing..