Shut Down Problem !

[vinman]

First let me start off with my system configuration.

Intel 2.4B 533 side bus 512 cache CPU
Gigabyte motherboard GA-8IXHP intel 850E chipset. lastest bios
F8. The MB supports H/T.
OS windows XP Pro.
Two western digital 80gig hard drives running at raid 0 with the MB on board promise 20276 raid controller.
1gig of PC800 RDRAM.
Two optical drives DVD and CDR burner.
One floppy drive.
One 7in1 card reader on other floppy bay.
350 watt dual fan enermax power supply.

I've been running this system for about year and a half with not a single problem, rock solid stable! Now comes the problem I upgraded the 2.4 to a 3.06B H/T 533 side bus 512 cache CPU and everything works fine BUT when I go to shut down about 50% of the time the PC hangs right on the part of the shut down that says (windows shutting down). But when I go to the bios and disable the H/T feature of the CPU this shut down problem never happens??????
Help this is driving me crazy! One last thing I am not overclocking
and my bios settings are at safe default.