To your choice of discs, change them. Arita are Riteks own brand for their low quality discs, B grade generally, and give it is 8x I would say they are G05, which has a poor reputation for longevity. Verbatim or TYs are a better choice.
You could go and look at the reviews of different drives in the drives section of the forum annd see which ones spark your fancy. Then ask for comparisons here. I like my BenQ but I also liked my NEC before it. I would go for anydvd for region free as it will work with any drive.