Network Manager hangs "waiting for authorisation"

The symptoms: a wireless network connection that normally connects without problems sometimes, maybe after suspension, hangs with the status "waiting for authorisation". There is no window asking for a password anywhere (the network manager should anyway have the password). This seems like a bug. Two home made solutions:

• Reboot your router
  It just works.

 

• New Connection
  This seems to be a working permanent solution. It involves re-creating the connection as public connection. Maybe not all steps are necessary. In Network manager:
  Manage Connections: Delete the existing broken connection. Really delete it, do not just edit it.
  Manage Connections: Add ("Add..." button) and then fill in a new connection name and the correct SSID and password as required;
  Select "Connect automatically" and "System connection";
  Restart the router (it was necessary here!).
  In a terminal use the following command:
  sudo iwlist wlan0 scanning essid
  (where SSID is the SSID of your network and wlan0 is the interface for the scan. See this post)
  The wireless network is found and connected automatically.

Note: using Kubuntu with kernel 3.0.0 but according to google's world there are people using other distros (SuSe, Ubuntu) reporting the same problem.