Today, out of the blue, it happened that Reeder (a very nice RSS client for Mac OS X) just stopped working.
Every time I opened it, it was asking me for my Google Reader credentials. Even if I issued them correctly, it would keep on giving me error about being unable to connect to Google services.
Very quick fix: open Keychain Access application and remove the line corresponding to Reeder application and then restart Reeder.
Easy, isn’t it?