I have found a problem when upgrading to ubuntu 11.10 regarding the network manager
After upgrading the wireless connection didn’t work I thought it was a problem related to the wlan driver.
Finally I have followed below steps for resolving the issue
Open the terminal
Alt+F2 type gnome-terminal
then run the below command
$sudo apt-get remove –purge network-manager
uninstalled the networkmanager
$sudo apt-get install wicd
Installed the wicd for fixing the issue.