I think that is not at all a software issue. As Dr. Who already pointed, Memorex DL discs are pretty low quality media, and playback issues are the most frequent side-effect of low quality discs.
The best solution is to use proven quality discs, i.e. Verbatim.
Maybe you can try to use the memorex media (even if not advisable at all) reducing the amount of data you write on these discs.
For example, you can try to put not more than 7GB on them, so the most external part of the disc (i.e. the lowest quality part) will be not written