Itunes problem

I aired this problem some time ago, but perhaps I didn't elucidate it clearly enough. I'll try and do better.

Mac mini-mid2007; Snow Leopard.

Yesterday I ran the computer all day without opening Itunes; everything works fine; no noise from speakers.

Today I opened up Itunes and it played the songs fine for about an hour. Then it started making an interrupting noise which sounds rather like the end of an lp record at the end of play continuing to rotate and pop. The frequency of the popping seems to vary day to day--not a loud pop; just disconcerting and interrupts the music. I quit Itunes and the sound continued through the speakers. After less than an hour , the speakers went quiet. Open up Itunes, and the same sequence repeats.

Would surely appreciate any help, and thanks in advance.

Michael

There is a later version I could get. You say reinstall--is that equivalent to updating Itunes to the latest version? Thanks

One more bit of information. When I unplug the speakers, the internal speakers sound fine. The problem is not the external speakers, as they sound fine on another computer. When I plug back in the external speakers, it sounds fine for a few minutes before the interruption starts again.