Windows 7 x64 cannot kill Skype

Solution 1:

Unkillable Skype is caused by one of the Skype threads trying to close a handle to the Ancillary Function Driver (/devices/AFD).

This close call hangs and never returns. When you try to kill the process, the I/O request gets cancelled, but the cancellation also hangs. The process cannot quit until its threads return, and the thread cannot return until the cancellation completes, hence process termination is impossible.

You can confirm this with a kernel mode debugger. See this TechNet blog article for details.

You need to use a remote debugger, because Skype causes some unhandled exceptions which will freeze windows otherwise.

The probable cause is some bug in some network filter driver.

Solution 2:

Try again Taskkill with these switches:

taskkill.exe /f /fi "status eq not responding"

You may also look in HKU\Control Panel\Desktop and change the value of WaitToKillAppTimeout from the default value of 16000 (milliseconds) to a lower value (but not 0!) and HungAppTimeout from the default value of 4000 (milliseconds) to a lower value (but not 0).