Track skipping/lag playing FLAC

If I don't touch the mouse, moc plays FLAC fine. If I click away from the console, and interact with the os gui there are 1-2 second audio skips. ~6 per minute if simply using web browser. the os is on a different HD than flac, could that be the cause? (worked fine in foobar2000 on win7, never had issue with slow data transfer between my multiple HDs.) 4gb ram, intel i-7 (quad-core). fresh format + install of ubuntu on OS HD. new to linux. sending audio via hdmi. any idea why moc buffers or stops playing the songs for a few seconds when i do anything at all? do you know if that is a characteristic of the terminal console, moc, or my setup?
thanks.