Freezing during OS update. What do I do?

Hi, I started with the OS 1.21 and am now downloading the 1.23 OS update. The MPC has frozen on 98% and hasn't moved for hours now. What do I do? I haven' turned the MPC off yet only because I have told my MPC won't work if I turn it off during an update.

Please help
Thanks
Rory

Cut and paste the OS to the ROOT directory of the ORIGINAL CF CARD that came with the 2500.
With the unit OFF, power up while holding the WINDOW button down.
It should prompt you to load up the new OS. Hit F6 for DO IT.