You indicated from your email that the following error was showing in the eventlog:
The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID
{A9E69610-B80D-11D0-B9B9-00A0C922E750}
to the user NT AUTHORITY\NETWORK SERVICE SID (S-1-5-20).
This security permission can be modified using the Component Services administrative tool.
Based on a little research, this can be caused by IIS being installed after service packs on the base OS. The fix is to apply service packs again (or use Windows Update) to make sure IIS binaries are in sync with the rest of the OS.