Back up problem

[seagull]

I've backed up a copy of Shawhank Redemption using DVDshrink and Nero.

Quality etc is great.

Except I was watching it last night and after about 15min into the picture would "stick" and then jump forward anywhere from 6-10 seconds further into the movie.

any idea's what going on

I got a phillips 6200 DVD+R burner and a Phillip stand alone DVD ( only by chance not planned that way)

I'm using Digimedia (i think's it) disks

I've done some other back ups but have not yet had a chance to check them yet.

thanks