Spread Spectrum Clocking is a way to lower electromagnetic interference or EMI. This is important for storage solutions that are required to pass FCC and other agency certifications. All current Serial ATA disk drives implement SSC (some allow you to turn this feature on/off). However, some older SATA drives do not implement SSC. All Sonnet Serial ATA host adapter cards support SSC but will also work with disk drives that do not.
This does not happen often, but sometimes the driver caches do not get purged and the new SATA driver does not get loaded correctly from ROM.
Try this:
1) Delete and empty trash for the following file and two directories:
/System/Library/Extensions.mkext (a file)
/System/Library/Caches/com.apple.kernelcaches (a directory)
/System/Library/Caches/com.apple.romextensions (a directory)
