If you're using NCover and it fails with "Profiled process terminated. Profiler connection not established" then check out Kiwidude's troubleshooting suggestions. In my case the problem was that I wasn't registering Coverlib.dll before I ran the NCover task.

I made a few changes to the buildfile for the NPresent tests so that it registers it before running, and unregisters it afterwards:

<target name="tests.run">
    <exec program="regsvr32" commandline="${tools-dir}/ncover/Coverlib.dll /s" />
    ...
    <exec program="regsvr32" commandline="${tools-dir}/ncover/Coverlib.dll /u /s" />
</target>