You may have already checked this problem in Google where there are several causes and solutions shown for different operating systems. but the most likely cause seems to be that there is a defective program attached to the right click context menu. I suggest you read the appropriate solutions for Win 7. First thing to try is to see if it happens in Safe Mode, if it does not then you have at least ruled out a driver problem.
WPA2 hack: How secure is your Wi-Fi?