Cannot run tests with Typemock 7.1.15 on Win8 with VS2012

I have just done a new clean install of Windows 8 and VS2012 on my development PC. After installing Typemock 7.1.5 I cannot run any tests within the VS2012 Test Explorer (I am using the Typemock provided C# sample application). I get the error

------ Run test started ------
Exception has been thrown by the target of an invocation.
========== Run test finished: 0 run (0:00:05.2558535) ==========

I installed VS2010 in the same PC and opened the same project, all the test runs OK, so it is an issue with VS2012 and Isolator

If I disable Isolator mocking (using another sample solution that contains tests that use Isolator and some that do not) the test run and pass other than then isolator based ones 9as expected). However, I then enable mocking ALL the test fail to run with either the same error as shown above, or just appears to hang waiting for something.

This would appear to be similar to https://www.typemock.com/answers/11400/?show=17895#a17895 but I have am running 7.1.15 which is mean to have the correct namespace file. I have also checked the contents and it seems Ok

Any suggestions?