Hi guys, I have installed WinUSB.dll driver for some device on WinXP 64 bit . Here is some problem that when my app use WinUSB.dll API run there is some message which shows winsub.dll is not found . But winusb.dll is right there in Windows\System32 , what's the problem ? This problem did not happen on WinXP 32 bit . Thank for your helping .