EDIT: Solved. Brute force. Uninstall/reinstall did it. I dunno.
I've searched Atmel's support site, Googled, searched forum here.
I've used this MK II ISP for a long time, but apparently never under Windows 7. AVR Studio 4.18 SP3 is installed, works OK.
Win 7 says it cannot find USB driver. I did "repair" install of Studio. I don't see a "driver" for an Atmel STK with which the MK II ISP would be found. Win 7 Control Panel lists the device by name in the USB list, but no driver found.
Sorry, basic question.