I have this problem with my machine. I run RAID 0 (striped) using the onboard nVidia RAID controller and the nVidia driver. It causes my machine to hang on shut down. I tried to find a solution but could only find one or two others with the problem.
I can't say exactly what causes it, however, it is predictable for me. My computer does not shutdown cleanly whenever my machine has used the swapfile at some point since booting up. Now that I have 2GB RAM this rarely happens any more. With the 512MB I used to run it happened pretty much every time.
To see if you have the same problem try turning off the swapfile temporarily and see if it stops happening.
I haven't tried updating to the newest drivers, but if they don't help, I don't think there is a solution. At least for me, I know when it is going to happen.
I can only assume that the driver shuts down the RAID array before windows has finished with the swapfile (perhaps it expects to unmount it from the paging system or something)?
Hope this helps,
Martin
buggery i need more memroy i only have 1gig thanks for the help