Selenium

[shiva upreti]

I wrote this code in python for submitting a login form:

<code>
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
driver = webdriver.Firefox()

driver.get('some url')

elem = driver.find_element_by_name("username")
elem.send_keys('13103666')
elem = driver.find_element_by_name("password")
elem.send_keys('as')
driver.find_element_by_name("btnSubmit").click()
#nothing happens from here
print driver.page_source
print "test"
</code>

After clicking on submit button, a message is displayed on the same page whether login was successful or not. 
However after clicking on submit button, I lose control over the web page. I can't use any selenium functions now like 'driver.find_element_by_name()'.

Initially everything works fine. I can enter username and password using selenium as written in my code, but once I click on submit button or press return key(tried both using selenium), any script written after that(involving web driver) doesnt seem to work. Even driver.close() doesnt work.
This is the form I am trying to submit:
<form name="frmHTTPClientLogin" target="_parent" method="post" onsubmit="return checkSubmit();" action="httpclient.html">

The submission is successful, however after submission I cant verify if login was successful or not because of the issue I posted above.
Do I need to switch web handle? If, then how.

Any help will be highly appreciated.