I changed it back to the original name, but I'm still getting the same error
... Any suggestions???
Thanks in advance... You guys are great!! 
That is normal behavior, on every name change a new certificate is generated by the server automatically. Each time the certificate is generated it will have a different check-sum. You probably are prompted with a message saying if you would like to trust this certificate (for this time only, permanently or not), am I right?
The warning you are shown is not an error but a warning, I think, that the certificate is a so-called self-signed certificate and that the trusted authority is not known. Normally certificates are signed by trusted authorities (e.g. VeriSign or others) yours is not as it is generated by your server, therefore you receive this warning.
By installing the certificate on your client, you will not be warned (in th future). Name changes or certificate changes will then result in unaccessible server-manager pages (until you remove the old certificate or install the updated one).