I too have a plextor 12/10/32a and for most games this is enough with Clone Cd to backup the games I purchase, however Safedisc2 does seem to defeat even the plextor on this.
There are two parts to the answer.
1. Read the readme file which states that the Cd must be in the first CDRom drive (i.e. if you have a burner on X: and a CDRom /DVD on Z: then place the CD in X
2. To make an exact image with your plextor, what I suggest you do is to use Clone CD to make an image on your hard drive and to then use a program called Betablocker (this is available at GCW) to repair the weak sectors on the image before you burn the CD. It worked for me.