Windows 10 out of memory (4GB) with no programs running

I've got an almost completely fresh install of 64-bit Windows 10 on my wife's laptop. It has a Core i5 processor and 4 GB of memory.

If I leave it on for too long, it gets slower and slower. It fills up the RAM and then it fills up the page file. And then it'll show the error:

Your computer has run out of memory.

I'm not confusing "available" with "free" or anything like that. The system is literally out of memory.

It appears Windows 10 isn't showing all of the processes running on the system. Task Manager and Resource Monitor both report no processes running. But the disk utilization and RAM utilization totals are bright red because they're at 97% RAM and 100% disk. A look at the “Processes” tab shows nothing using more than 10 MB of RAM, and there's only maybe two dozen total background processes, all using no disk.

So I want to know:

1. Are there processes that Windows hides?


2. If do, how do I find them?


3. What's causing my memory problem?

I set the computer to reboot. Five minutes later, it's still trying to close down Task Manager and Resource Monitor. How can this happen? What possible reason could exist for a fresh install of an operating system to have this problem?

Okay, let's look at some pictures.

[edit] Nope. Poolmon doesn't show the problem. I'm hitting 4 GB usage again, and poolmon doesn't show it:

[edit] Two more, from the next commenter, running RAMMap:

Notice that "process private" is HUGE (which I have read is memory dedicated to a single process) and yet, no related processes show up in the process list.