The problem connected with home recording are media brand (Verbatim is a really good quality one), recorder (Plextor is also on top) and other accidentally inconvenience, so copies are not always the same.
I suggest downloading this simple pc application and test if your DVDs are free from errors; try also to simply start in the player.
http://www.kvipu.com/CDCheck/download.php
Hope it will be useful.