problems with grub and serial console

[Tomoki Taniguchi]

I have new box that i am setting up as a XEN server.
It is a HP ProLiant ML 150 G3.
a quad-core xeon 1.6Ghz
with 4GB or ram.

I went through a feisty SERVER (x86) install.
everything seems to be working ok
i apt-get update, then apt-get upgrade.

so far everything is working as it shoud.
I install ubuntu-xen-server.  reboot
working fine...

then i try to set up serial console output in grub
i first set it up as i normally do
<snip>
serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=10 serial console
<snip>

the system starts to boot get to
<snip>
GRUB Loading stage1.5.
GRUB loading, please wait...
<snip>
and stops....  i tried rebooting a couple of times but with the same result.

i boot from a recovery cd and editted /boot/grum/menu.lst
i tried the following settings
<snip>
#serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=10 serial console
<snip>
serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
#terminal --timeout=10 serial console
<snip>
serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=10 console
<snip>
serial --unit=0 --speed=38400 --word=8 --parity=no --stop=1
terminal --timeout=10 serial console
<snip>

but all resulted in the same the only way i could get the system to properly
boot was to take serial settings completely out of the config
<snip>
#serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=10 console
<snip>

other serial output seems to be working fine, bios, xen, and even ubuntu,
only the grub serial setting causes a problem...

Any clue as to what could be problem?
for the time being i have taken serial output out of grub.

TIA,
Tomoki Taniguchi