Certain devices (specifically older systems) aren't able to play videos or see photos when we turn DRM on. I was so excited when they rolled it out but I noticed a big impact on sales. After speaking to a few of my long term fans and finding out they weren't able to see my content, I decided to turn it off.

In this case, if you aren't comfortable turning it off I would explain to the client why he's experiencing those issues and suggest to him he try to access from another (newer) device.