Cold Tap will not turn off to stop water?

After the cold spell my Cold Tap, when turned on, will work. However, when i go to turn it off, it wont turn off. I have to then turn off at mains, turn on tap completely for a moment, THEN it turns off (when the pressures gone) I then turn the mains back on. How do i fix this? Is this simply a washer gone?

chris
February 2011