On a Windows Server 2003 computer that has the 64-bit version of the operating system installed, you cannot see CA (Certification Authority) Web Enrollment pages.
You will experience this behavior if the server is running WSUS (Windows Server Update Services) or any other service that requires the 32-bit version of .NET and that causes IIS (Internet Information Services) to run a 32-bit work pool.
This problem occurs because the CA Web enrollment pages require a 64-bit work pool.
To resolve this behavior:
1. Open Internet Information Services (IIS) Manager in the Administrative Tools folder of the Start menu.
2. Expand <Computer Name>.
3. Right-click Web Sites and press Properties.
4. Select the ISAPI Filters tab.
5. Select the filter that has a name that starts with ASP.NET.
6. Press Remove and OK.
NOTE: This workaround causes services that use the 32-bit version of Microsoft .NET to stop working.