Sound stops working periodically on laptop. Windows issue?

Hi!

I have until Feb 28/tomorrow to return this laptop for my money back so I'd be so happy to have this sorted out quickly.

Today the sound started cutting out randomlySeems random to me at least. When it does this, I check the mixer and it registers no sound on the vertical adjuster. Simultaneously, when I try to play youtube videos they will start ( or start and restart) and then stop, showing an error message. Sometimes video works but no sound. For a minute I was told I had no internet connection. And then I leave it alone for a while, try again, and voila, the sound has returned. Ech! What could be causing this?

The laptop is an Asus Q550 LF and I really like it otherwise so I hope it gets it's act together. I am not downloading torrents/p2p etc and running plenty of security ( Malwarebytes, CC Cleaner, McAffee ). My internet is 9mbs shared with another laptop

Because there is such a time crunch on evaluating this machine I am asking as well in Software and Hardware. Hopefully that is ok with Tech Guy. Thanks so much anyone that might have suggestions!