firmware
Perhaps you need to update your firmware for the cd burner at Plextor's website.
Also search for a small utility called Clony XXL...it works great with clone cd. The only drawback is the latest version is in dutch, but not too hard to figure out.
Also, due to copyright laws, if you you live in the US or the UK, clone cd cannot read some sectors of protected cd's that use safe disc or safe disc2. This is easily fixed by opening regedit and do a search for AmplifyWeak. Change the value from 0 to 1. You can then copy safe disc2 cd's.
I am attaching a small utility that will tell you what kind of copy protection a particular cd has (if any) to give you a guidline on how to burn it.
Good luck.