Running Selenium RC tests in firefox in offline mode

Question

Is there a way to run Selenium test in offline mode? If I set the offline mode in the firefox profile, selenium is stuck at selenium.start(). I'm using the python client driver. The code is as below

sel = selenium('localhost', 4444, '*firefox', 'file:///home/user/selenium/selenium-python/client-driver-1.0.1/inputs/input.html')
sel.start()
sel.open('file:///home/user/selenium/selenium-python/client-driver-1.0.1/inputs/input.html')