how to kill a thread in python

I have a very simple plugin I wrote for freevo. below is the plugin. it will shutdown your computer after your avi file has finished playing, kind of like a sleep timer.

#!/usr/bin/env python

import os
import time
import commands
import thread

import plugin

from gui.PopupBox import PopupBox
from gui.ConfirmBox import ConfirmBox

class PluginInterface(plugin.ItemPlugin):
    """
    this plugin will power down your system using the command
    "shutdown -h now" after your avi file has finished.
    you can enable it by adding this to your local conf file
    plugin.activate('video.autoshutdown')
    """
    def __init__(self):
        plugin.ItemPlugin.__init__(self)

    def actions(self, item):
        self.item = item
        if item.type == 'video':
                    return [ (self.confirm_start_timer, 'engage autoshutoff') ]
        else:
            return []

    def confirm_start_timer(self, arg=None, menuw=None):
        ConfirmBox(text=_('engage autoshutoff for the following avi file\n\
                                         "%s"') % self.item.name,
                   handler=self.start_timer, default_choice=1).show()

    def start_timer(self, arg=None, menuw=None):
        box = PopupBox(text=_('you must start your avi file within ' \
                                               'one minute to prevent the shutdown' \
                                               ' to begin' ))
        box.show()
        time.sleep(6)
        box.destroy()
        thread.start_new_thread(self.run_timer,())

    def run_timer(self):
        while True:
            time.sleep(60)
            if commands.getoutput('ps -ewf').__contains__(self.item.filename)== False:
                os.system('shutdown -h now')
                break

the run_timer method is started as a new thread using this line of code

thread.start_new_thread(self.run_timer,())

the run timer_method checks at an interval of every minute to see if an avi file is playing, if the avi is no longer playing, it will send the computer the shutdown command. I would like to be able to abort the shutdown if possible. Is their a way to kill the thread that I started, maybe some sort of kill method?

Note: this is untested.

Wrap it in an exception:

try:
    thread.start_new_thread(self.run_timer,())
except KeyboardInterupt:
    sys.exit(1)

thanks for the suggestion :-)