Encryption failures when upgrading to SQL Server 2005

We recently upgraded from SQL 2000 to SQL 2005 on WINDOWS 2003. The entire upgrade process has run pretty smoothly aside from encryption. We have ASP.NET 1.x apps that connect to an internal server but fails when encrypted. We have tried all of the steps available on the MS KB and still have not resolved the issue.

On How to: Enable Encrypted Connections to the Database Engine by Microsoft, we find the following: To configure the server to accept encrypted connections:

1. In SQL Server Configuration Manager, expand SQL Server 2005 Network Configuration, right-click Protocols for , and then selectProperties.
2. In the Protocols for Properties dialog box, on the Certificate tab, select the desired certificate from the drop down for the Certificate box, and then click OK.
3. On the Flags tab, in the ForceEncryption box, select Yes, and then click OK to close the dialog box.
   
4. Restart the SQL Server service.

The problem is when we get to Step 2, there are no certificates available in the dropdown box. This problem is solely the result of installing SQL Server 2005. The apps were successfully encrypting data connections prior to the installation. All internal and non-encrypted connections work correctly. What can I do to get certificates to appear in the Certificate tab of the Properties dialog box?