Question about patents (RE: Microsoft and Linux)

I have a question related to this article. The jist of it is that Microsoft claims that Linux (and other open source projects) violate 250 of their patents, but isn’t naming the patents or taking legal action. My question is whether Microsoft (or anyone else) loses any legal standing regarding their patents if they don’t defend them?

There is the defense of laches, which is an affirmative defense. However, this isn’t often used against patent claims.

In my understanding, the courts would expect a patent holder to practice some kind of dilligence in protecting one’s patents, including warning infringers that they appear to be infringing and including making it easy for somebody practicing your invention to figure out the fact that they are indeed practicing your invention.

But if a patent holder does not protect their patents, usually nobody else does.