We have two AD9958 EVAL boards and one AD9959 EVAL board. All were working fine and suddenly began not working. One AD9958 and the AD9959 all of a sudden didn't recognize the external clock input (though it was there and at the right level) and the other AD9958 all of a sudden stopped working (didn't recognize the USB interface) when the 3.3V supply was pulling a lot of current (1.5A). In that case, the USB I/O interface chip was burning hot. Not sure why all of these are failing. Any suggestions?