can't compile Y-combinator

When I try to compile the following code with GHC-6.4,
ghc takes much time and seems not to terminate.

module Fix (fix) where

newtype T a = PsiInv{ psi :: T a -> a }

fix :: (a -> a) -> a
fix f = g (PsiInv g)
    where g x = f (psi x x)

Trac metadata

Trac field	Value
Version	6.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	ResolvedWon'tFix
Component	Compiler
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