Pioneer Elite SC-61 High Pitched Buzz

Hello,  I have a Pioneer Elite SC-61 receiver which I purchased in 2012.  I have my Apple-TV, DVD and FIOS Cable box all switched through it.  It's connected to a Samsung QN75Q70RAFXA 72" TV. 
In the last few days I've had a problem.  The sound is fine for about 10 minutes, then it starts to cut out for a few minutes.  Then it emits a high-pitched buzz.  It happens when any of my sources are used (DVD, Apple-TV, Cable, Radio).  Any idea what could be causing this?