I have somehow muted all the tabs in my google chrome. Youtube and other flash players are playing video, but there is no sound. In Window 7 Volume mixer I can see Google chrome icon and it has muted icon there. But clicking that icon unmute sounds just for a second and then it's muted back on. Seems that chrome itself or some of it extensions are turning mute... Update: How do I mute certain tabs in Chrome? question seems related, but I don't have MuteTab extension installed in Chrome.