you should:
1. contact the openMSX crew for that
2. use a more recent openMSX version

I think it's still running on openMSX 0.3.4.

ahh, you want to run the old DEMO!!!

if the OS makes diferentiations about upper-case and low-cases in filenames, please check all the filenames if match with the configs files and the BAT.

anyway you can take away the DSK image and the ROMS and the configmachine file and add to your working openMSX

in my PC with win98SE the package works perfect!

I use Windows Server 2003, that one doesn't bother about case-sensitivity, much like Win98. Point is, there is no romsdb.xml file at all!
I don't have a working config of openMSX, cos I don't want it. I have NLMSX which is sufficient in most cases, and blueMSX. Furthermore I prefer working on the real thing over emulation. But I really wanted to see the MNBIOS demo, but I guess that's a no-go without openMSX. Too bad, really... But I'll wait then till it comes with ATA-IDE support

is not necesary to run the demo that file
that message is just a WARNING!!! but is not FATAL!!

C:\WINDOWS\Escritorio\MNBIOS Release>openMSX -machine MNBIOS -diska mnbios.dsk -
diskb mnbios.dsk
info: Using specified machine: MNBIOS
led: power = off
led: caps = off
led: kana = off
led: pause = off
led: turbo = off
led: FDD = off
warning: Warning: couldn't open romdb.xml.
Romtype detection might fail because of this.
warning: couldn't find file: ""
warning: couldn't find file: ""
led: power = on
led: caps = on
led: FDD = on
led: FDD = off
led: FDD = on
led: FDD = off
led: FDD = on

This is the console from my computer, and it works...

So, openMSX don't work with win 2003 server?

you need to talk with openMSX gurues to asks for that.

[D-Tail] i can send you a newest version with the latest openMSX version...

please, sendme and email and i will reply this with the ZIP