A leaky faucet thread

At my home we have an annoying problem with the bathroom sink leaking when the hot water is turned on. The sink has knobs for hot and cold water. Turn the hot water's main knob on from below the sink and no matter how off the actual sink knob is, the faucet runs. So if you need hot water you have to turn it on from below the sink, use it, and turn it back off. The cold water has no problems.

Help! Surely someone in this crazy land of INTERNET can help!

Surely someone from the crazy land of plumbers can help!