Windows NT 4.0

[Wilson Birney]

I have a windows NT 4.0 raw image that when converted with qemu-img to 
qcow2 or vmdk fails to boot in qemu with no obvious error using the 
following:

qemu-system-i386 -m 128 -cpu pentium -hda f.qcow2
It just hangs at 'Booting from Hard Disk...." and pegs out a cpu core.

This same image boots just fine in vmware Workstation and virtualbox 
when i convert to a vmdk.

Any ideas on what could be causing this or what to do to diagnose it?

Thanks
wpb