You may get a Page cannot be found message when you browse aspx pages in a Windows Server 2003 environment.

That is because in Windows 2003, all the webservice extensions are "Prohibited" by default to ensure security.

To resolve this, do the following steps:-

1. From your Run command, type inetmgr and press enter.
2. Expand the appropriate nodes in the IIS to locate the "Webservice Extensions" Node
3. Click on the same.
4. You will find a list of "prohibited" extensions in the right.
5. Click on ASP.NET and "allow" it

That should resolve this issue.

 If ASP .Net is not installed, first install it from MS. Then follow these instructions (for .Net 2 as example here):
Click on start then select Run. Copy and paste this command then click okay. That will reregister ASP.NET to IIS
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspn et_regiis.exe -I

from IIS go to ASP.NET tab and change the asp.net version to 2.0XXX
(in IIS go to the specific virtual directory of the web application for which you are recieving this error. Right-click on it, and in the properties there will be an ASP.NET tab which you can toggle to .NET)

From your Run command, type inetmgr and press enter.
Expand the appropriate nodes in the IIS to locate the "Webservice Extensions" Node
Click on the same.
You will find a list of "prohibited" extensions in the right.
Click on ASP.NET and "allow" it.