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#11
Use this tool to determine via the hardware ID what the unknown Device is: Hardware Identification
You need to get through the WD Lifeguard Extended CD test or the HD is suspect.
Run Disk Check first to check file system as it sometimes affects the HD test. The two repairs can return a failing HD to service. In this case you need to know if its reponsible.
If not I'd run Prime95 on the mobo: CPU - Stress Test with Prime95 - Windows 7 Forums