17 R5, Chrome + YouTube video playing automatically

I've had my 17 R5 for about 8 months and I love it. Lately I've encountered a strange behavior that I cannot find a cause for.

A few weeks ago, I watched a video on YouTube of an Unreal engine rendering of Grizzly Hills, complete with music. However, every few days, even if the laptop is closed, Chrome will suddenly open a new browser tab to that YT video and start playing it.

This is particularly alarming when it happens at 3 AM and I'm asleep, because suddenly my wife and I will be awoken to music emanating from the living room where I keep the R5.

This doesn't appear to be a security thing. Power settings on the R5 tell it to go to sleep when the lid is closed (although occasionally I've spotted the LED lighting activate, even when the lid is closed, which leads me to wonder if the Win10 power setting is being ignored or overridden somehow). The fact that somehow the link to this video is still lingering in memory somewhere is odd, especially since I've cleared Chrome's cache, verified that the default home page is a blank page, closed Chrome, rebooted the laptop, etc. all as part of regular use.

Any thoughts as to why this could be happening?