This has been resolved.
1. The problem had nothing to do with the brand of disk drive; it is exactly the same with Seagate. It probably occurs with all Advanced Format drives.
2. The generic Microsoft AHCI 1.0 driver works without problems. However, it is possible to cause Windows to recognize the SATA hardware as Intel by downloading and executing the file infinst_autol.exe from the Intel website here:http://downloadcenter.intel.com/Detail_ ... _autol.exe
This is an executable file, which detects Intel hardware, and installs appropriate infs, causing Microsoft to apply the appropriate device drivers. The actual SATA driver is Intel specific, but signed by Microsoft.
I could not detect any difference in performance between the generic Microsoft AHCI 1.0 driver, and the Intel driver. But if the Middleton BIOS was burned, it might enable SATA 2.0.
Since the correct Intel driver is available, Lenovo should update the X61 support packages to install it. The "Intel Matrix" storage driver wrecks file systems, and should not be on the Lenovo support site.