I'm pretty new to this, but there are two possibilities that I can think of.

Boxwood can have an unusual urine-like odor, but it doesn't have red berries.
Here's a link with pictures:
http://landscaping.about.com/od/evergreenshrubsbushes1/p/english_boxwood.htm

Hollow red berries sounds like an english yew.
Another link with pictures:
http://landscaping.about.com/od/evergreenshrubsbushes1/a/japanese_yews.htm

I strongly suspect that the cats are marking their territory on a regular basis, and you just haven't caught them at it. It would only take ONE male cat to create this kind of stench. I'll be that if you take some steps to repell this kind of behavior, that the odor will eventually go away.

In other words, the plants are not the problem!

I also think it's a cat marking its territory. We had one do that to us last year. We thought it was a gas leak. The confirmation was the presence of cat poop in the area of the smell.

I think you have Yews. They have and always will smell like cat pee to me.

It's a yew tree. They smell strongly of cat urine, and they also attract cats who also urinate on them. I'd get rid of it if I were you.