Usually when this happens it is due to the original host being 32 bit and the new host being 64 bit and you are being hit with the SMP kernel update problem of Windows.
Try booting in safe mode and see if it starts. If so then shut down the guest and make sure that IO APIC is not checked. Then start the guest in safe mode and do a system restore to just before you tried it on this system.
Or you can follow this link and use HALu viewtopic.php?f=6&t=27494&p=122752#p122752
to change the kernel mode for you