[ubuntu] Software-center install button always greyed out

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http://ubuntuforums.org – Mine is a Ubuntu 11.10 fresh install, and since the beginning I've noticed that I can't install any software from the Software Center because the install button is always greyed out and unclickable. What could the problem be? Also, sometimes when I'm doing something, a dialog box pops up saying that the login-keyring did not get unlocked when I logged in and tells me to input my password. What does this mean? Also, I can't get the wallpaper on my desktop to change when right-clicking an image and setting to to wallpaper, but setting the wallpaper in the 'change desktop background' option work (Hardware)