If it's what I think it is, it's Windows 7 being Windows and not playing nice with the southbridge chipset. (personally had lots of similar more severe issues) All you can really do is try uninstalling AHCI/IDE/RAID drivers and trying new drivers directly from the OEM website. If it doesn't work, try third party drivers or changing from AHCI/IDE/RAID (whatever you used to install Windows) to something else and try again.
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