Windows 7 Firewall services consuming all CPU

"Wireshark finally runs on Windows 7 64-bit, and I find my answer.

When running wireshark during one of these incidents on my laptop, the Interface Capture screen shows that my TAP-Win32 Adapter V9 is accumulating packets at a very high rate.

Capturing that interface shows that the packets are a sequence of DHCP requests: Discover, Offer, Request, NAK -- that were all running in 0.0159 seconds and then repeating.

In this highly specific case, the subnet (and interface, upon reflection) is one that is used by the OpenVPN client installed on my laptop. In some cases when unsuspending, especially when unsuspending onto a wireless network, the OpenVPN client ""connects"" and then gets scrambled up while the network settings are settling. I frequently have to disconnect, then connect the OpenVPN client in order to use it.

Remembering all this, I disconnected and reconnected the OpenVPN client. This immediately was rewarded with a DHCP Discover-Offer-Request-Ack sequence followed by the usual noise that Windows sends along network connections. More importantly, the CPU usage immediately ceased.

The desktop system involved also had a OpenVPN client installed on it and was probably the source of those issues too."

"In my case, Internet Connection Sharing (ICS) service stucks in ""Starting"" status.

Open Run dialog (Windows + R) and key in services.msc to open Services, find Internet Connection Sharing (ICS) and disable it.

Restart and enjoy :)."