I have followed Microsoft's instructions for custom 404 pages in SharePoint by setting the web application's `FileNotFoundPage` property. I am now still getting a 404 error if someone types a site collection name incorrectly. For example if the user goes to `sharepoint/sites/test` and "test" is not a site collection then they will still get a 404 error. I have tried catching this with a httpModule also, but it looks like the request is returning a 200 code instead of a 404. 

Several of the blogs mention this same problem but I have not seen any solution for it.

This seems to be working within a site collection context only, i.e. `http://MyMOSSServer/sites/siteA` if sites is a wildcard inclusion managed path and siteA doesn't exist in MOSS then this URL will NOT trigger the custom 404 error page set to `SPWebApplication.FileNotFoundPage` property.

Thanks.