Check the Device Manager to see if there is a "Standard Dual Channel PCI IDE Controller" under "IDE ATA/ATAPI Controllers" with two "ATA Channels" that have a yellow warning mark on it. If so, select the Standard Dual Channel PCI IDE Controller, click "update driver" and navigate to "Sonnet Tempo SATA QIO PCI Express Adapter" and install it. (Note that this requires that you first run the Qio driver installation.)
This is a Microsoft Windows driver bug with some 64GB CF cards. Sonnet is working with Microsoft to resolve this issue. (64GB and 128GB CF cards work fine with Qio and Qio-CF in OS X.)
A partial list of cards Sonnet has tested:
Patriot Pro CF 266x 64GB/128GB card is recognized under Windows
Lexar Pro 1000x UDMA 7 64GB/128GB card reports itself as 32GB
SanDisk Extreme Pro UDMA 6 64GB/128GB card reports itself as 32GB