Facing problem with Winpcap ? I used to use Cain long time ago on my Windows 7 PC. It was working fine but yesterday I installed the cain again on same windows and found some errors in cain. When tried to start ARP and Sniffer a message came up " Unable to open Winpcap driver : The system cannot find the device specified." I thought may be I haven't restart my PC thats why this messsage is coming because during installation it said that Winpcap will work properly after reboot. So I rebooted my PC and again the same problem. This time I took a closer look into the message and i found the solution from the message itself. message clearly said that Unnable to open the driver. Here are the simple steps you can follow to fix this problem. Step 1: Goto configuration Step 2: Select sniffer Step 3: Select the right driver. (Usually its the driver which is showing the IP of the network which you wanna sniff.) Thats it. No need to restart again...