error with Firefox Binary 'The browser appears to have exited'

Sun Apr 12 15:44:06 EDT 2015

I have problem with selenium and Firefox when i run my code below:
 from selenium import webdriver
 from selenium.common.exceptions import TimeoutException
 from selenium.webdriver.support.ui import WebDriverWait
 from selenium.webdriver.support import expected_conditions as EC
 from bs4 import BeautifulSoup
 import urllib2,cookielib
 import re
 from pyvirtualdisplay import Display
 import urllib
 import urllib2
 import httplib2
 from os import system
 display = Display(visible=0, size=(800, 600))
 display.start()
 name = 'test'
 driver = webdriver.Firefox()
 driver.get("http://example.com")
 driver.switch_to_default_content()
 inputElement = driver.find_element_by_name("name")
 inputElement.send_keys(name)
 inputElement.submit()
 print "Please wait for 5s to get results.."
 content = driver.page_source.encode("utf-8")
 html = str(content)
 soup = BeautifulSoup(html)
 print soup
 display.stop()
 driver.close()
And i get this error:
 Exception in thread command9:
 Traceback (most recent call last):
 File "/usr/local/lib/python2.7/threading.py", line 551, in __bootstrap_inner
 self.run()
 File "/usr/local/lib/python2.7/threading.py", line 504, in run
 self.__target(*self.__args, **self.__kwargs)
 File "plugins/help_plugin.py", line 165, in handler_search
 search_number_ar(type, source, parameters)
 File "plugins/test.py", line 230, in search_test
 driver = webdriver.Firefox()
 File "/usr/local/lib/python2.7/site-packages/selenium-2.45.0-py2.7.egg/selenium/webdriver/firefox/webdriver.py", line 59, in __init__
 self.binary, timeout),
 File "/usr/local/lib/python2.7/site-packages/selenium-2.45.0-py2.7.egg/selenium/webdriver/firefox/extension_connection.py", line 47, in __init__
 self.binary.launch_browser(self.profile)
 File "/usr/local/lib/python2.7/site-packages/selenium-2.45.0-py2.7.egg/selenium/webdriver/firefox/firefox_binary.py", line 66, in launch_browser
 self._wait_until_connectable()
 File "/usr/local/lib/python2.7/site-packages/selenium-2.45.0-py2.7.egg/selenium/webdriver/firefox/firefox_binary.py", line 100, in _wait_until_connectable
 raise WebDriverException("The browser appears to have exited "
 WebDriverException: Message: The browser appears to have exited before we could connect. If you specified a log_file in the FirefoxBinary constructor, check it for details.
my code running in vps and i use selenium-2.45.0 and firefox-38.0b3 . I try alot of ways to solve my problem but nothing working with me. I try to update selenium and i try to downgrade firefox and alot of solution.
Just to know when i run my code for the first time it work but when i run it again it show me the above error.
I have Python2.7 .
I hope someone help me.