Hi Mike (Oates),
It sounds like you have one of my pre-release versions. What version do you see when you do Process->Modules->ManageModules?
If you examine the folder containing those modules, which files do you see named anything like Arcsinh or ArcsinhStretch?
The pre-release versions were called Arcsinh, not ArcsinhStretch.
If you do Resources->Updates->Check For Updates, are you sure that ArcsinhStretch does not appear?
Mark