Program execution fails with runtime error.

I ran a very memory consuming program on a 32GB machine with the following RTS arguments:

-H18000M -S -c

hoping that I could avoid all the copying. However, I got the following message:

internal error: update_fwd: unknown/strange object  27330425
    (GHC version 7.0.3 for x86_64_unknown_linux)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort

As a side note: with just the -c option, I had run into a Segmentation Fault.

Without any run-time options, the programs fails to complete succesfully before running out of memory.