There have been a handful of trial users experiencing a missing method exception under the 3.4.x versions of NCover. That exception looks something like the following:
Exception Type: System.MissingMethodException
This exception generally occurs because the user does not have at least service pack 1 (SP1) of the 3.5 framework installed. Installing the service packs for the 3.5 framework has resolved this issue in each case I’ve encountered so far.