I have the same scale. It worked great under Vista.
I did a CLEAN install of Windows 7 Ulimate. The device was detected, and drivers installed. Under "Devices & Printers" it is in the unspecified category, listed as "USB Electronic Scale"
Detais on the driver:
HID-compliant device
Driver Provider: Microsoft
Driver Date: 6/21/2006
Driver Version 6.1.7600.16385
under "Driver details" button, it says "No driver files are required or have been loaded for this device"
It is reported as "working properly" in the status.
The software installs fine, and when I try to run it, I get the exact same error message.
I've also tried setting compatibilty mode to "XP" and to "Vista" and get the same error.
I haven't tried "Virtual XP" mode yet, but that will REALLY be a stretch if I have to load a virtual session every time I use the scale....
Any other ideas?