Atheros Wireless Driver Windows 10 there. To cllear this error, you need to open the file called npf.sys which is located at * C: Windows System32 Drivers in Windows 7. Follow the below guide to open the npf.sys file. Firstly, make sure that you have installed winpcap, if you didn't install it, just go to its official site and download it for installation: Next, find cmd.exe which is located at * C: Windows System32 in Windows 7, right click and 'Run as administrator'. When it opened, input net start npf, then the NPF driver is successfully opened. That is,the file npf.sys is opened. Lenovo Touch Screen Driver Windows 10. At last, restart Wireshark, it will be OK now.