Hi,
It seems like a version mismatch between Typemock.ArrangeActAssert.dll and Typemock.dll
Please check the gac (C:Windowsssembly) in the server. If it contains Typemock.dll you should remove it from the gac.
Your tests should reference Typemock.ArrangeActAssert.dll in the deployment directory.
Please let me know if it helps.