This problem may occur if the private key and certificate do not match.
To resolve this problem, specify the correct private key for the certificate. Compare the modulus of certificate against the modulus of the private key to see if they match. Follow these steps:
View the certificate modulus using the following command:
openssl x509 -noout -modulus -in certificate.crt | openssl md5
View the key using the following command:
openssl rsa -noout -modulus -in privateKey.key | openssl md5
Verify the following:
Verify that the certificate and private key is saved in Notepad and that it has no trailing spaces.
The "modulus" and "public exponent" portions in the key and the certificate must match exactly.
Make sure you aren't using the default server.key file.
You should also check the httpd.conf / httpd-ssl.conf file to make sure that the directives are pointing to the correct private key and certificate.
If they do not match, please generate a fresh CSR and share it with us so that we can reissue the certificate.