If you run an X38 or X48 chipset, or anything else running ICH9R or 10R, and run Windows 7, then watch out for the latest Windows Update "Optional" driver update.
WU is deploying "Promise Technologies Raid 1+0 JBOD" drivers which is crippling those chipsets. I lost my raid arrays but was able to get them back by reverting to the driver provided in the IMSM from Gigabyte's website dated 2010/4/29.
I am referring to this driver...
Promise Technologies Inc. - Storage - Promise AHCI Compatible RAID Controller
Installation date: 29/09/2010 12:48 PM
Installation status: Successful
Update type: Optional
Promise Technologies Inc. Storage software update released in September, 2010
More information: Winqual Help
Help and Support: Select a Product Solution Center
Sounds about right. Windows 7 crippled my wireless card with their "new" update -.-
-Update- A customer's PC running the same chipset but a sole drive has reported that after performing windows updates last night, their system has become unbootable.
Seems like it is effecting non-raided drives that are attached to the controller as well. You should be able to boot from a UBCD and download the appropriate driver to the RAM Disk and install from there.