Ladies & gents

Upgraded CPU in desktop from Pentium D to Core 2 Duo - motherboard and other hardware supposed to be compatible with this so just assume that for a moment.  BIOS (which is the latest version) recognises new chip OK but a few seconds after Windows screen, hard drive stops and the Windows loading bar keeps going but no action and no boot.

I have googled extensively and it seems people tend to think this is a video driver issue - thing is can only start Xp in safe mode and cannot install new drivers (nor run Windows update and check if something critical missing nor run the Intel driver utility from their website either).

Am I missing something simple here like a driver or some other piece of software/firmware that I need to install?

I have tried repairing the Windows installation (thinking it might be a DLL file or something) and that didnt work.

As I said, this setup should work but I feel I am missing something simple here?  Any ideas?  I am not a techie expert but have a reasonable grasp of things.  Any help most appreciated as I dont want to go back to my Pentium D!