Hello. Can you post your operating system? Also is it 32 or 64bit?
The only thing I can think of, make sure you are running the pc version and not the mac version. If that is not it, please try describing your issue with the term "Ren'Py" into google. Haremwatch uses this engine, which is used by many other games to run. It is a universal game engine, so perhaps your error has been solved by others.