Maybe I have a second idea on solving this problem.
I recently had the same sptd.sys bug (no proper restart possible).
My system run perfectly with 2 onboard IDE, 1 SCSI pci and 1 RAID pci controller, SW:EaW and CureRom etc.
I changed my burners firmware and everything stopped.
No solution offered here worked.
I searched the registry and found 4 (four) entries regarding sptd.sys. I deleted all and reinstalled the sptd.sys.
I researched the registry and found (as expected) only 2 entries for sptd.sys.
System booted up properly. Everything is fine again
murx