Backfire

I'm trying to copy my Dragon Age: Origins DVD as a backup. It has no copy protection, just a serial key. I assume I just make the image as a .iso and burn the image to a dual-layer dvd (selecting the .mds file of course). I tried to do this with Alcohol 120%, but it stopped burning at 47% completion, so I'm wondering if theres anything I may be doing wrong - It could be that I'm running too many programs while burning or it was a faulty DVD. Thanks in Advance.