Running VS Unit Tests stops IIS
We recently ran into this problem where we discovered that running our VS unit tests was killing IIS.
As with all problems, I like to break things down to the simplest scenario I can find and as such created a brand new unit test that did nothing to see if that still caused the problem – it did.
So knowing that it had nothing to do with any code that was web dependent I knew to start looking elsewhere.
Turns out the problem is caused by enabling code coverage on projects that are dependent on IIS – e.g. a web project.

The simple solution is to disable code coverage on the problem-causing project OR alternately remove the dependency on IIS by modifying it to use the in-built Cassini web server.