I have stm32F407 discovery board and I have downloaded and installed the ST_LINK USB driver on my laptop running window 10, but when I plug in the discovery board, the error message pops up saying the USB driver is not recognized, in the device manager, it showed unknown USB device. I tried several ways,like uninstalling the unknown USB device, updating the driver, installing the driver again. Restart the computer and plug in another USB port, nothing seems to work. It worked before, right after I soldering the header pins onto the discovery board, My laptop couldn't connect to the board. I tried a new cable today, I still have the same problem. 
Can you help me to find a way to solve this? It's really painful to be stuck in the same place again and again. Thanks!
