Playing copied dvds

I have been burning alot of dvds using nero 6. The problem is the copied dvd will freeze but will work fine in other dvd players. I am using a brand new pioneer dvr111 burner, tdk dvd+r and have tried changing the reading and writing speeds. Ive aldo defragged and tried freeing up hard drive space. I am aware that some dvd players do not play copied discs at all, but i dont think that’s the problem as my copied discs usually work fine.

Which DVD media are you using to make your backups?