Background Description
You are able to login to Project Web Access, but you cannot connect to Project Server using Project Professional 2007 directly or when you try to perform functions in PWA that require PWA to launch Project Professional, such as opening projects from the Project Center. The system returns the error "invialid userid/password" and you are certain that the URL you entered for your Project Server account is exactly the same one you use to load PWA.
Resolution
This condition can occur if anonymous access is enabled in IIS for the site collection hosting Project Web Access. To resolve this problem, uncheck anonymous access for this site in Internet Information Services Manager.