Right guys need a little help here

as some of you may remember from an earlier post i have instaled a Plextor DVD-RW (still waiting my super drive) anyway i have some Total Traing DVD's which i know are MAc compatible but which won't run on my my MAC they work fine on a Windoze PC but not a MAC. (Well this one anyway)

I therefore ripped the DVD to my MAC then used Toast to Burn a New DVD selecting for MAC only and stil they won't run.

Is this problem down to my DVD-RW rom or the DVD it's self.