Pyongmu

I have been running RAID0/ RAID5 combo on 4 400GB NS Seagate disks using the Matrix RAID feature of the ICH9R chipset for about a year now. The os and the progs are installed in the RAID0 and all valuable data in the RAID5. All was fine until recently when I began receiving reports of disk failure during the boot I can still boot to windows so is obvious the RAID0 portion of the "bad disk" is still working. In windows, the Intel Matrix Storage Console reports the RAID0 is functioning normally whereas the Raid5 is degraded.
I ran Seatools on the compromised disk but it failed to identify any problems. Any ideas?