I'VE STOPPED THE CRASHING!!!!!!!
Finally, MI4 does not crash!!!
FYI, if you have a Sound Blaster Live, you will have Sound Blaster Emulation at a Creative Misc Device in your device manager, disable this (don't remove it) and run the game in Direct3D. I have a Geforce and it cured my problem. There has been known probs with Blaster Control and a SB Live, (bit stupid being the same company and all!). Hope it helps anyone!