Error message when you try to request a certificate in Windows Vista or in Windows Server 2008: “The filename or extension is too long. (0x800700CE)”
When you try to request a certificate on a computer that is running Windows Vista or Windows Server 2008, certificate enrollment may fail. Additionally, you receive the following error message:
The filename or extension is too long. (0x800700CE)
This problem occurs when the Subject Name field of the certificate is longer than MAX_PATH (260 characters).
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB983557.