Ubuntu – Disabling Network-Manager-Gnome wireless scanning when connected

1) Yes. Or at least, it's always done the same for me!

2) Not directly. You can edit the connection to prevent it connecting automatically, which is one workaround.

Alternatively, when it asks for the password just click Cancel, then select the network again from the Network Manager icon; it will reconnect as normal (using the stored password).

You can look at System --> Administrator --> Log File Viewer, Under "dmseg" file to see if something with the authentication process is wrong

Some more experienced people will suggest to harvest the power of terminal by doing something like :

cat /var/log/* | grep network-manager > network-manager-output.txt

I hope you can find a solution to your problem