Boot problem after first install

[Moritz Jodeit <moritz_(_at_)_jodeit_(_dot_)_org>]

Hi,

I try to install OpenBSD on my laptop (Toshiba Portege 3440CT).
But everytime I try to boot the first time after install, it prints:

Invalid system
Change disk and press a key
(Translated from german)

I tried "fdisk /mbr", OS-BS and using the following commands after install:

fdisk -i wd0
cp /usr/mdec/boot /boot
/usr/mdec/installboot -v -h 15 -s 63 /boot /usr/mdec/biosboot wd0

But nothing helped. Does anybody know how to fix this?
Here are some details, if that helps...

I do a network boot with the pxegrub file, since I can't boot with
floppy nor cdrom. During boot, it prints the following about my harddisk:

wd0 at pciide0 channel 0 drive 0: <TOSHIBA MK6014MAP>
wd0: 16-sector PIO, LBA, 5729MB, 12416 cyl, 15 head, 63 sec, 11733120 sectors
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2
wd0: no disk label

Install runs ok, but gives some errors. When I choose to use the entire disk
for OpenBSD, I get the following:

Updating MBR based on BIOS geometry.
fdisk: sysctl: Device not configured
Only LBA values are valid in ending cylinder for partition #3.
Only LBA values are valid in ending cylinder for partition #0.
[...]
Cylinder values are modified to fit in CHS.
wd0: no disk label
fdisk: 1> Here is the partition information you chose:

fdisk: sysctl: Device not configured
[...]
disklabel: no disk label
WARNING: Disk wd0 has no label. You will be creating a new one.
[...]
# using MBR partition 3: type A6 off 63 (0x3f) size 11733057 (0xb30841)
disklabel: Can't get bios geometry: Device not configured

At the end I get the following error:

installboot: Unable to get BIOS geometry, must specify -h and -s

If I try to boot, I get:

Using Drive: 0 Partition: 3

Invalid system
Change disk and press a key

I then tried to boot with a DOS floppy and run "fdisk /mbr".
It seems that this fixed the first problem but I still got the following
when booting:

Invalid system
Change disk and press a key

Next thing I tried was to run the following commands after the install
finished:

fdisk -i wd0
cp /usr/mdec/boot /boot
/usr/mdec/installboot -v -h 15 -s 63 /boot /usr/mdec/biosboot wd0

But after booting I get the same errors, I got the first time. My last
idea was to install OS-BS bootloader. But this seems to have the same
effect, as the fdisk /mbr.

TIA,
Moritz Jodeit