MSI K7NT2 Delta proble, help requested

I have built a new pc with the following specs
AMD 3000xp cpu
MSI K7NT mobo
2 x geil 3200 512mb ram
Maxtor 120gb 8mb buffer
ATI Radeon 9800 pro
Pioneer dvd writer
Creative Live value soundcard
AMD 3000xp cpu
Windows XP Pro with service pack 1
When i set the fsb to anything other than 100, just after the boot screen
i get the helpful message 'ntldr missing, press alt cntrl delete to restart'
I have reinstalled windows from scratch, and tried repair, but nothing seems to help.
I have used live update to get the mobo up to date.
Can anyone give any advice at all?????????????????????????????????????????
Any tips appreciated.
Thanks in advance

Please can you confirm that the model code for the motherboard is K7NT because when you search on msi's website for that specific model, no results are returned.

Best Regards

Lee