Computer Tips - Firefox gives me this error: "Your certificate contains the same serial number as another certificate

Date: 2008feb1 Product: Firefox Q. Firefox gives me this error: "Your certificate contains the same serial number as another certificate issued by the certificate authotity. Please get a new certificate containing a unique serial number." for a site I setup with self-signed certificates. How can I fix this? A. Delete the certificate and re-accept it.
Tools > Options > Advanced > Encryption > View Certificates