TweetDeck for Linux, for example. Refused to start on me recently because it couldn’t find or access the location where I had saved my encrypted details. The problem is caused by Adobe Air not being able to find a running daemon for Gnome Keyring or KWallet, or a corrupted wallet database.
Full details here http://kb2.adobe.com/cps/492/cpsid_49267.html – works for me!
In my case, simply restarting KWalletManager worked fine. And restarting TweetDeck of course – it’s unable to pick up the fact that the wallet is available.