Laptop issues

I have a Dell, and lately, if I leave a webpage open for a few minutes without touching anything, the whole thing freezes up. Nothing works except for holding down the power button to force a shutdown.
Either that, or it just restarts itself if left alone long enough.
It doesn't happen every single time, so I'm wondering if this is a sign of something bigger brewing.
Should I take it to a repair shop?

Reinstall macOS

How?
If you aren't interested in explaining, no worries—it's all Greek to me.

Maria James11 said:How exactly?
If you aren't willing to walk me through it, then I'm completely in the dark here.

Well, there are honestly millions of tutorials floating around the internet, and if you check Vimeo, you'll find just as many videos providing step-by-step guidance. You could simply print out a guide and get to work. You'll just need a DVD or a USB drive with macOS on it, along with the necessary drivers for your laptop. Once you purchase macOS, you can just download the drivers directly from the Dell website.

Do you have an installation disc for macOS? Start by attempting a clean install of macOS.
Before doing that, check the health of your hard drive. Check the CPU temperature to see if it’s overheating.
The issue could be anything—macOS, the RAM, the processor, or the hard drive.