What would cause my PC's sound to shut off?

[kuurt]

Sometimes after having my computer on for a while and the audio has been working, it suddenly stops working.  And so far restarting the computer has got it to start working again.  But I'm wondering what is causing this problem.  When I go to device manager it says I have "High Definition Audio Device" and "Realtek High Definition Audio".  I'm not sure why there is two - does it require two audio drivers?  Why do I have two?  I bought these speakers awhile back and the brand name is blackweb.  I'm not sure if the speakers required their own drivers which are separate from my sound card's drivers.  Both of the audio drivers say they're working fine, but I don't know what the problem would be if not the audio drivers.

[DaveLembke]

I'd test the system RAM to make sure you dont have a minor memory issue that hits a flawed address that causes the issue. Memtest86 is good test for this.

Two audio devices may be if you have a video card added to system instead of integrated video the video card itself can support sound on the HDMI port and so the video card has sound built into it for the system to be able to pass audio over HDMI.

[patio]

The reason there is 2 id the hi def one is the Win interface for the audio driver...totally normal.

[kuurt]

Ok, I ran the memtest86 and it didn't find any errors.  However it was saying that I had 4 CPUs and 1 active.  It said only one was active for testing.  Does that mean my other 3 CPU's are not working, or does it just not use all of them for the test? 

In addition to my sound turning off,  my browsers are starting to slow down and even freeze up (stop responding) at times.  This is a refurbished computer I bought from Walmart's website a few months ago and everything loaded really fast when I first got it even with many tabs open at time.  Which is getting more difficult to do these days.  Sometimes when it is not responding, my computer is making noise like it's processing something, but I don't know what.

I have deleted all cookies, browser history, and temporary internet files.  Ran disk clean and defrag.  Windows 10 antivirus never finds anything.  Malwarebytes doesn't find anything.