New PX-716A, Can't install Roxio 7.0 from Plextor Disk



I just purchased a Plextor PX-716A and was trying to install the supplied software. The Roxio Easy CD DVD Creator 7.0 software will not install. It gives me an error message “Unable to find certificate file”. I do have an older verion of Roxio easy 5.0 on the machine, is this causing the problem? The other software on the supplied DVD did install. I tried Plextor but they won’t be back until Monday or Tuesday if they take the holiday. Any help would be appreciated