since upgrading to Ubuntu 13.04, I get a window asking for a password for my email address. The window appears after logging into the desktop. The window is titled "Zugangsanfrage" (access request) and "Legitimierungsanfrage" (legitimation request), asks for the password of the acount my email address, gives no further information and doesn't let me do anything until I enter a password or cancel the dialog. It has the option to store the password in the key ring, though. I can start new apps using the starter bar, but I cannot use them move windows, or type into other windows. I cannot even make a screenshot.
I have not even the slightest idea which password to give. Does it ask for my web-mail password or for the ubuntu-one password (where my login is the email address) or is it just a phishing app (but how did I get it). I tried entering some random characters and it is happy.
Update: I added a screenshot: