Nasty gunzip problem on MPC8313E-RDB

We have 2 MPC8313E-RDB REVA4 boards.

u-boot always fails to uncompress certain compressed files.
Either the board will hang or a checkstop occurs.
The problem occurs on both our MPC8313E-RDB REVA4 boards.
Probably memory is overwritten at the end of RAM (where
u-boot is relocated to). When using a jtag debugger no
problem occurs.

The stock u-boot (shipped by Freescale) has the problem,
any custom built u-boot (v2008.10 or v2009-rc3) also
has the problem.

I tested with u-boot.v2009-rc3 on another board (a PQ2FADS
board). The problem doesn't occur on this board.

I would like to find this problem and I could use all the
help I can get. I'm a bit stuck at the moment.

It's not the watchdog, nor the compiler toolchain. The
watchdog is completely disabled anyway and other compiler
toolchains (including the ones from Freescale) make no
difference.
I already tried to raise the u-boot malloc() area, it makes no
difference either.

when compressing using bzip2 (either --best or --fast) no problem
occurs.
The problem occurs only for gzip compressed files which have