Here are a couple of the ones I have had problems with.

Digital Image Pro- Creating 'Tuft' Fibers
Quite a few of the latest tutes

I also checked a few I had had problems with before (some of the older ones) and they seemed to be better - unfortunately I can't remember which ones I looked at exactly so I'm not 100% sure! I just wanted to make sure it wasn't something I was doing wrong - if it's just that the pictures sometimes don't come up or some need fixing, that's fine!!!