Windows 7 Chrome : Volume getting mute automatically

[ss0007]

Hi ,
Recently, I noticed there is no sound from any Videos played inside Chrome. I noticed in the Volume Mixer, the volume of Chrome is muted.
I tried to un-mute it. But, in the next second, the Volume gets muted automatically !

Have you peoples noticed the same problem ?
I am on Chrome 10.0.648.133 (Official Build 77742) , Windows 7.