Everytime I double click winghci.exe an error message CreateGHCiProcess failed with failed with error 2 pops. I assume the installation hasn't completed setting environment variables successfully since cmd C:\>ghci ends up with no command found either. Could anyone help posting changes that might take place during the installation or any solution to this?
To complete the incomplete answer: add the path of the bin directory inside your haskell platform folder, e.g. C:\Programs\Haskell Platform\2012.2.0.0\bin, to your PATH. That should be all.