It’s difficult to comment this since I don’t know what is NDIS3PKT you use. However, if checking unchecking it fixes the problem then it may appear to be the problems reason. It looks that WinpkFilter is stable, since you don’t need to reboot the system in order to restore the functionality. Of course problem can be in the application, if it will stop reading packets from WinpkFilter you will get the “frozen LAN” effect.
