In GHCI execute

let powers = 2:map (2^) powers
powers

When calculating the fourth element of the list, you get the following error message:

<interactive>: internal error: getMBlock: mmap: Invalid argument
    (GHC version 6.12.1 for i386_unknown_linux)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

If you have trouble reproducing the bug, try substituting an other number for 2 in the code, e.g. I have also got that error message when I defined powers as:

let powers = 4:map (4^) powers

and

let powers = 13:map (13^) powers