This bug was reported at and being tracked in Launchpad at https://bugs.launchpad.net/ubuntu/+source/network-manager-applet/+bug/158017

"After a long hibernation cycle (one night) nm-applet is not granted access to the proper gnome-keyring anymore. By itself it is not wise enough to try to unlock the keyring again, ergo ask for the passphrase again. This does not happen when I hibernate only for a short time (5 minutes).

Specifying the WEP/WPA passphrase by hand does not work either, because nm-applet tries to save the phrase before it attempts to connect to the network. Failure in saving automatically results in failure to connect. This is a misconception as well I think! If I know the passphrase I should be able to connect, no matter what!

However, I can solve the problem with killing and restarting nm-applet. It then asks for the passphrase again. (I restarted the keyring-daemon as well, don't know if that was really necessary)."

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Additional information:

"Both /etc/pam.d/gdm and /etc/pam.d/gnome-screensaver contain:
auth optional pam_gnome_keyring.so
However, only the former contains:
session optional pam_gnome_keyring.so auto_start
That's how it should be according to the documentation:
http://live.gnome.org/GnomeKeyring/Pam
Is gnome-keyring-daemon supposed to be killed on hibernate? If that's the case, then it should be sufficient to append auto_start to the end of the auth line in /etc/pam.d/gnome-screensaver, since that pam module checks if the keyring daemon is already running and doesn't start it again if it is.

After a little investigation, it seems gnome-keyring-d _isn't_ dying on hibernate, at least not always. So either it's dying sporadically for some reason, or there's some other reason why that line in gnome-screensaver's PAM config (which should unlock the default keyring) doesn't prevent network-manager from thinking the keyring is still locked."