When renewing ssl certificates in IIS 6, you cannot use the option "renew certificate" within IIS console.
Reason: Within the CSR (certificate request) only the domain information will be stored.
Following action is required:
1. Create a new website inside IIS
2. Create the CSR from this website
3. Finish the request by applying the certificate.
4. Remove the certificate from this website (the certificate will stay on the webservers certificate store!)
5. Replace the new certificate with the old one on your website
6. Remove the website you created within point 1