Why is my screen turning black when it's been on for a while?

I have an Acer Spin S5. I use this laptop constantly. This issue first started when the machine was in strenuous use (after a few hours of data mining), but it’s become more and more common with time, often happening more than once a day when I simply have an arrangement of chrome, adobe reader and notepad open.

Sometimes, the screen suddenly goes black. When this occurs, the fans will usually fire constantly for a few hours, before shutting off. Sometimes, the keys light up when touched. Sometimes, they don’t. The button to make the keys light up, or stop the keys lighting up, does not work. The button to make the computer sleep, or tapping the power button, has no effect. I normally just hold the power button until the computer goes off, and then start it all up again. As soon as it’s on, it’s as if nothing ever happened. I resume work,

This issue most often occurs when my laptop is low on battery, I plug it in, and leave. Although the first few occurrences (during data mining) occurred on battery power, almost every single time it’s happened recently is while charging, not on battery power, or while plugged in at full power (or even near full).

What is happening, and can it be fixed?