Could new motherbaord freeze W2K?

I am running Windows 2k Advanced Server on my network. I had to replace the motherboard and after receiving my replacement motherboard from the manufacturer I decided to change to a Celeron processor to as well. After rebooting I get through the Bios but Windows freezes at the splash screen after the Starting Windows bar reaches the end. Could it be that Windows doesn’t recognize the processor or the motherboard? Or what else could it possibly be?
And what can I do to remedy the problem? I’m really stuck here because this server is serving my website! Please Help!!!