software center got stuck/not responding

software center got stuck/not responding

A few days ago I installed Ubuntu 13.04. After installation I ran few
programs one by one to see that if everything worked fine.
At that time the Software Center ran and it listed some software in the
window. But now two days after installation, when I open the Software
Center it does not list any software at all. I closed it and ran it from
terminal by typing sudo software-center as suggested in some forums, the
terminal shows the following error:
root@engrali-OptiPlex-760:~# sudo software-center
2013-08-13 21:23:50,366 - softwarecenter.ui.gtk3.app - INFO - setting up
proxy 'None'
Traceback (most recent call last):
File "/usr/bin/software-center", line 130, in <module>
app = SoftwareCenterAppGtk3(options, args)
File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line
338, in __init__
self.icons)
File
"/usr/share/software-center/softwarecenter/ui/gtk3/session/appmanager.py",
line 66, in __init__
self.oauth_token = helper.find_oauth_token_sync()
File "/usr/share/software-center/softwarecenter/backend/ubuntusso.py",
line 141, in find_oauth_token_sync
sso.find_credentials()
File
"/usr/share/software-center/softwarecenter/backend/login_impl/login_sso.py",
line 75, in find_credentials
self.proxy.find_credentials(self.appname, self._get_params())
File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 70, in
__call__
return self._proxy_method(*args, **keywords)
File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 145, in
__call__
**keywords)
File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in
call_blocking
message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not
receive a reply. Possible causes include: the remote application did not
send a reply, the message bus security policy blocked the reply, the reply
timeout expired, or the network connection was broken.
please, can someone help me to solve this problem?