I had exactly similar problem with my pc. Different motherboard and processor though.
It worked perfectly otherwise, but when I paused SH3 for example going for a smoke, computer was frozen. During play no problems. Only when paused system froze.
I installed new mobo and video drivers without help. The solution was to update bios. After the update systen has frozen null times.
Here's a link to HP's support pages where new bios can be downloaded.
http://h20000.www2.hp.com/bizsupport...EnvOID=228#120