no sound/sound

[zipidachimp]

hi:
I'm on my second install of mint 13 mate and still have this problem: the first boot of mint gives me no sound on youtube or other sites. when I reboot, the sound is OK. this effect was also on my first install of mate. hard to tell if the problem is my pc or my install. any ideas?
the second install was for another problem re: graphics, which has not reappeared on the second install.