TypeMock and WCF

I built a WCF service and a test who starts the host process of this service:

ServiceHost myServiceHost = new ServiceHost(typeof(MessageRelayContract));
myServiceHost.Open();
Thread.Sleep(3000);
myServiceHost.Close();

I want to test whether the default configuration of the service works or not. The test works fine on my dev machine.
Unfortunately the test fails on the build server with the following exception:

"System.AccessViolationException : Attempted to read or write protected memory. This is often an indication that other memory is corrupt."

As you can see I am not using TypeMock within this test - but the test assembly has other tests who do, so I need to launch TypeMock (using the TypeMockStart command in MsBuild). The test works fine when turning of TypeMock (but then of course other tests fail).

Is this a bug or a configuration problem? I'm using TypeMock 5.1 with the AAA concept.