System Hangs

Every time I unplug my ethernet cord from my PC the system hangs for 5 seconds or so and I have to restart to get it to stop. I've checked the device drivers for the network adapter and it doesn't say anything is wrong. The task manager shows that the CPU usage shoots way up every time the system hangs. Any thoughts on what might be happening? The drivers are all up to date on the network card.

Thanks for the reply, although, not sure if I made clear what the problem is-- When I unplug the ethernet cord, the system hangs for around 5 seconds every 30 seconds or so until I restart the system. If I don't restart, like I said, it hangs for 5 seconds in around 30 second intervals and I get extremely random spikes in my CPU usage as well, more often than the hang (it seems). It looks like an EKG going crazy.

Would not stopping the connection still cause this?