I can't answer that question in detail, but I can say that on Windows 2003 servers under x64 you must explicitly set up IIS to Allow Web Service Extensions for ASP xxxxx (32) applications. In a console window, type: cscript %SYSTEMDRIVE%\adminscripts\... SET W3SVC/AppPools/Enable32bitA... 1 Then proceed with the following steps: Open IIS; Web Service Extensions Click on Allow All Web Service extensions for a specific application Choose ASP Net vX.Xxxxx (32) Click OK In a command window ......