If you don't have backup for any data you don't want to lose, you'd better make it ASAP. It sounds to me like you have hardware problems in the RAM or hard drive area. If that's the case, you'd better be ready for that computer to stop working completely at any time until fixed.
I installed Windows 10 as soon as possible, and my pc has gone from crashing a couple of times a week to almost daily.
It doesn't matter what I'm doing or how long I've been online. Frozen screen, no Task Manager, manual shut down and then start it up and it's okay till the next time it crashes. This morning, it turned itself off, then back on, and then I got a black screen telling me something like the pc had no readable memory.
I'm thinking about going back to Win 7. I wasn't crazy about it, but at least it didn't crash all the time. And it also didn't require being started and then immediately restarted because it wouldn't recognize my ISP, which is another daily problem with Win 10.