Conflict with multiboot module 0

I have successfully compiled L4, so that the examples work, and have got 
my own little test user tasks to run as well.  However, when I try to 
run a slightly larger program as the roottask, I never even get to 
launch the kernel.  It dies with the message "Conflict with multiboot 
module 0\nPlease choose a different link base." The full output is:


grub> kernel /kickstart
, <0x800000:0x6600:0x149c>, shtab=0x808280
grub> module /x86-kernel
   [Multiboot-module @ 0x816000, 0x2b8c1 bytes]

grub> module /sigma0
   [Multiboot-module @ 0x842000, 0x16c66 bytes]

grub> module /rt
   [Multiboot-module @ 0x859000, 0x3957e bytes]

grub> boot
Starting up ...




KickStart 0.13.06
Detected multiboot compliant loader
 kernel    (0x00816000-0x008418c1)   => 0x00144040
  (0x00816000-0x00824e96) -> 0x00100000-0x0010ee96
  (0x00825000-0x0082ab00) -> 0x00110000-0x00115b00
  (0x0082b000-0x00835a70) -> 0x00116000-0x00120a70
  (0x00836000-0x008399e4) -> 0x00141000-0x001449e4
 sigma0    (0x00842000-0x00858c66)   => 0x00200000
_ (0x00843000-0x0084b410) -> 0x00020000-0x00028410
 roottask  (0x00859000-0x008196c)   => 0x008000000
  (0x0085a000-0x0088196c) -> 0x00800000-0x0082796c
     Conflict with multiboot module 0 (0x00816000-0x008418c1)
     Please choose a different link base
PANIC: FAIL in line 163



I have tried to work out how to solve this from the L4 source code, but 
not succeeded.  Could anyone please explain to me more exactly what the 
problem is, and give some guidance to fixing it.

Many thanks,

Adam Antonik.