speaker app hangs the other apps!!

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Hey! I'm a newbie with Ubuntu. I just downloaded it yesterday but have been facing this problem repeatedly. everytime I play some music on the system and if i try to control the volume from my laptop (external) as the volume has already been set as full in my system; suddenly a pop up comes up and it keeps blinking repeatedly, I tried my best to close it but it doesn't. This gets inconvenient as all the icons on the top panel (Applications, Places, System) dont respond when i click on them... I can't even type out anything in the browser then n need to restart the system because of that....