[ubuntu] Lenovo Thinkpad Edge E420s Volume Button issue

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http://ubuntuforums.org – I have Ubuntu 12.04 running on my Lenovo Thinkpad Edge E420s. My issue is that whenever I use the dedicated hardware volume buttons (up or down), the volume will go up the first time I press the button, and on the subsequent press, the volume will mute. If I press it again, the volume will go up, and on the subsequent button push, the volume will mute again. The down button volume has the exact same behavior. I've searched around the forum and on AskUbuntu, but I haven't found anyone with similar issue. Any suggestions on what I can look at to troubleshott this issue? (Hardware)