I have authored & copied toughsands of CD’s (650Mb’s & 700Mb’s) and DVD’s (DVD+R & -R & +DL) and have made very few bad burns.
There are many things you may do to insure that you make as few bad copies as possible.
1 - Don’t buy the cheapest disks you can find, try a few brands burn them and keep track of which yeilds the fewest bad copies, WHY? because some Recorders work better with some brands than others, usually i recomend Maxell and Memorex, but Memorex only for CPU’s they don’t perform well on DVD Players or CD Players, I know you burned on Memorex.
2 - NEVER MAX OUT THE BURN SPEED, If your drive writes at 16X and the DVD Burns at 12X You should burn at 8X or 10X to Maximize the chances of a good burn, ALSO, Doulbe Layer DVD’s have a MUCH LOWER BURN SPEED than single layer DVD’s with is usually 2.4X or 4X so check that IT IS VERY IMPORTANT.
3 - When you burn a CD or DVD don’t do anything else with your CPU so that there is no other task to interfeer with the burn to cause a bad copy.
4 - Make sure the disk’s read surface (Source & Destination when copying) are clean, it will save you a lot of agravation.
Additionally, some recorders work better with some brands than other and one disk that burns well with your burner may not work as well with your freind’s recorder, so if you have a brand that works well with your brand of recorder stick to them (recorder and disk).