Apparently during the upgrade from PRTG version 9 to version 12 the SSL certificates work a bit differently. This can be written up a bit better, but here is a brief overview. After the upgrade, the SSL (a purchased certificate) certificate no longer matched. I opened the "Program Files\PRTG Network Monitor\cert" directory and noticed that "prtg.crt" and "prtg.key" existed with new file modification dates while the old "prtg7.crt" and "prtg7.key" files still existed. I backed up the "prtg.crt" and "prtg.key" files and overwrite them with the "prtg7" files. I restarted the PRTG services and SSL was back in business with the proper purchased certificate.