Problem:
A user remotely connecting to a Windows Home Server computer configured with WebFolders4WHS may receive the following error:
The folder you entered does not appear to be valid. Please choose another
or a dialog titled "Select the certificate you want to use" that allows the user to select from an empty list the certificate they want to use to secure the connection.
Cause:
This error is caused by when a user connects using a domain name other than their configured yourname.homeserver.com name that the server's certificate is configured for.
Solution:
Connect to the Home Server using the yourname.homeserver.com domain name instead of another one unless a certificate has been generated for that name as well.
Read the complete post at http://ihatelinux.blogspot.com/2007/11/missing-certificate-with-webfolders4whs.html