Backups play ok at beginning, but then fail

I have noticed this weird problem with backing up DVDs. They start fine, play fine, until about the half way point, then they herk and jerk, and sometimes will get by that spot, sometimes not. So, could it be the media, being + or - R, or the burner getting tired. OR could it be a number of things.
Using Verbatim media.

Are you using Verbatim AZO disks (MCC mid codes) or are you using Verbatim “Life Series” disks? The Life Series use plain ol’ CMC mid codes, and aren’t favorites around here.

What speed are you burning? Do you have the latest firmware for your burner?

What process are you using for backing up? Which programs for decryption and compression (assuming you are burning to single layer dvds).

Also, you should try making a backup to the hard drive. See if it plays properly from the hard drive using something like VLC media player or Media Player Classic HomeCinema. This will eliminate possible problems from the decryption/compression process.