When stack sets the code page within cmd.exe to try and make GHC output appear correct, it actually makes it worse instead. The fancy double quotes that GHC uses end up totally garbled.

example garbled text:

D:\Dropbox\dev\fbmessageparse\src\Main.hs:11:21:
Not in scope: ΓÇÿhGetContentsΓÇÖ
Perhaps you meant ΓÇÿgetContentsΓÇÖ (imported from Prelude)

Using Windows 7 64bit, which might be the problem since the stack for windows builds are done on Windows 8.1, but the codepages should be consistent enough across windows versions.