stopping LoopCall and check if running

I have a question on LoopCall.

I have a process that uses a sequence of LoopCalls, once one finishes
I call the next to check for the next critical event to continue:

e.g.

    def checkForAvailableProfile(self):
        profile = fs_profiles_manager.get_next_available_profile()
        if profile is None:
            return
        else:
            self.checkForAvailableProfileLoop.stop()

        self.profile = profile

        logging.debug("using profile: %s", self.profile['name'])

        self.ff = FirefoxProcess(self.profile, self.params)
        self.ff.run()

        self.checkForEventsFileLoop = LoopingCall(self.checkIfEventsFileExists)
        self.checkForEventsFileLoop.start(0.5)
        self.state = self.STATE_WAIT_FOR_EVENTS

====================================================

The problem is that I'm getting errors, errors when I try to call stop
when stop perhaps has already been called.
I want advice on how to manage LoopCalls. So far I'm using state variables.
e.g.
self.state = self.STATE_WAIT_FOR_EVENTS

if something goes haywire or if the process is done I have a function
that cleans up all the LoopCalls so it's not checking constantly:

    def cleanExit(self):
        if self.state == self.STATE_WAIT_FOR_PROFILE:
            self.checkForAvailableProfileLoop.stop()
        elif self.state == self.STATE_WAIT_FOR_EVENTS:
            self.checkForEventsFileLoop.stop()
        elif self.state == self.STATE_WAIT_FOR_PROC_KILLED:
            self.checkIfFirefoxWasKilledLoop.stop()

        self.ff.cleanExit()


the above code is what I believe is causing my exceptions, but how
else do I check for the LoopCalls?



=====================================================

2011-08-31 12:30:11-0700 [FiresharkProtocol,1278,127.0.0.1] Unhandled Error
    Traceback (most recent call last):
      File "/usr/lib/python2.6/dist-packages/twisted/application/app.py",
line 348, in runReactorWithLogging
        reactor.run()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 1170, in run
        self.mainLoop()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 1182, in mainLoop
        self.doIteration(t)
      File "/usr/lib/python2.6/dist-packages/twisted/internet/selectreactor.py",
line 140, in doSelect
        _logrun(selectable, _drdw, selectable, method, dict)
    --- <exception caught here> ---
      File "/usr/lib/python2.6/dist-packages/twisted/python/log.py",
line 84, in callWithLogger
        return callWithContext({"system": lp}, func, *args, **kw)
      File "/usr/lib/python2.6/dist-packages/twisted/python/log.py",
line 69, in callWithContext
        return context.call({ILogContext: newCtx}, func, *args, **kw)
      File "/usr/lib/python2.6/dist-packages/twisted/python/context.py",
line 59, in callWithContext
        return self.currentContext().callWithContext(ctx, func, *args, **kw)
      File "/usr/lib/python2.6/dist-packages/twisted/python/context.py",
line 37, in callWithContext
        return func(*args,**kw)
      File "/usr/lib/python2.6/dist-packages/twisted/internet/selectreactor.py",
line 156, in _doReadOrWrite
        self._disconnectSelectable(selectable, why, method=="doRead")
      File "/usr/lib/python2.6/dist-packages/twisted/internet/posixbase.py",
line 194, in _disconnectSelectable
        selectable.connectionLost(f)
      File "/usr/lib/python2.6/dist-packages/twisted/internet/tcp.py",
line 519, in connectionLost
        protocol.connectionLost(reason)
      File "/usr/sbin/fireshark.py", line 101, in connectionLost
        self.cleanExit()
      File "/usr/sbin/fireshark.py", line 43, in cleanExit
        self.checkIfFirefoxWasKilledLoop.stop()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/task.py",
line 171, in stop
        assert self.running, ("Tried to stop a LoopingCall that was "
    exceptions.AssertionError: Tried to stop a LoopingCall that was not running.

2011-08-31 12:30:22-0700 [-] Unhandled error in Deferred:
2011-08-31 12:30:22-0700 [-] Unhandled Error
    Traceback (most recent call last):
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 1170, in run
        self.mainLoop()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 1179, in mainLoop
        self.runUntilCurrent()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 778, in runUntilCurrent
        call.func(*call.args, **call.kw)
      File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py",
line 944, in unwindGenerator
        return _inlineCallbacks(None, f(*args, **kwargs), Deferred())
    --- <exception caught here> ---
      File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py",
line 823, in _inlineCallbacks
3, in _inlineCallbacks
        result = g.send(result)
    exceptions.AttributeError: 'NoneType' object has no attribute 'send'

2011-08-31 12:30:28-0700 [-] Unhandled error in Deferred:
2011-08-31 12:30:28-0700 [-] Unhandled Error
    Traceback (most recent call last):
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 1170, in run
        self.mainLoop()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 1179, in mainLoop
        self.runUntilCurrent()
      File "/usr/lib/python2.6/dist-packages/twisted/internet/base.py",
line 778, in runUntilCurrent
        call.func(*call.args, **call.kw)
      File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py",
line 944, in unwindGenerator
        return _inlineCallbacks(None, f(*args, **kwargs), Deferred())
    --- <exception caught here> ---
      File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py",
line 823, in _inlineCallbacks
        result = g.send(result)
    exceptions.AttributeError: 'NoneType' object has no attribute 'send'