Thanks to Cora, who made a suggestion that I actually followed (!!!) and I repositioned the unit. No more buzzing since then. Connie It’s a HP TouchSmart 520 PC with Windows 7. The computer and monitor are all one thing (no separate CPU system unit). I love it. Lately it has started buzzing, kind of in a rhythmic wave ... it’s not really loud, but it’s there. If I put my hand on the top of the monitor while it’s buzzing, it stops. It doesn’t do it all of the time, but too often for me.