Some of these are missing a disc, due to it probably still being in the DVD player. So, take notice of what is missing:

Dexter Season 1 - Missing disc 2

Breaking Bad Season 1 - Missing disc 1

Entourage Season 8

The Big Bang Theory Season 4

Psych Season 6

How I Met Your Mother Season 2 - Missing episodes 9-16 out of 22 epidsodes