USB 2.0 Woes on Intel D865PERLL

Just got this motherboard along with a 2.6 P4 w/ HT and 512 of DDR400 running in dual-channel mode. Hi-Speed USB was initially disabled in the BIOS. After loading Windows XP, installing the motherboard drivers from the included CD-ROM and installing SP1a, I enabled Hi-Speed USB in the BIOS and rebooted, and Windows loaded new drivers for the USB controller, but when I tried the only USB 2.0 device I own (a Sandisk keydrive) it reported as malfunctioning and would not be recognized. All my USB 1.1 stuff (webcam, printer, digital camera, CF reader) worked fine, and the keydrive worked fine when Hi-Speed USB was disabled in the BIOS. I then flashed the BIOS to the latest version and installing motherboard driver updates directly from Intel's site to no avail. I finally ended up hosing the hard drive, manually enabling Hi-Speed USB in a newly re-installed Windows with SP1a as was explained in an insert that came with the board, and installing the newly downloaded motherboard drivers without first putting the old ones in, but the same thing happens; keydrive works fine with Hi-Speed USB disabled, but fails when it is enabled. Any suggestions?