Hi again SMD;
This last article kemical posted was a fascinating read. It may be a bit advanced for you, nonetheless it's certainly worth exploring as it's very well written and there's a lot you could learn from it about how memory works in your PC.
Hopefully, you will gain some insight there and lead you to a fix. If it does not, you might consider looking at your hardware and even testing it. Josiah asked you if you tested your RAM sticks back in POST #2, but you never answered that question for us (this is kemical's post, and he is helping you, but thought I'd chime in since you're still having the problem). If you haven't tested your RAM sticks, here's where we usually recommend you do it from:
MEMORY DIAGNOSTICS:
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Using the Memtest 86+ test overnight on each of your RAM sticks individually, and then all the RAM sticks together can often find failing or intermittently failing RAM memory fails, including memory leaks. If Memtest finds any errors on individual sticks or all sticks when tested together, your RAM stick(s) have failed and must be replaced!
What's important to realize is that failed RAM sticks can cause errors that mimick software errors and symptoms and often the only way to eliminate that as a possible source of the problem is to Test your RAM stick(s) all of them. If no errors are found in Memtest, then at least you know the error is quite likely in a driver or from a software service or process that is failing, or weird stuff in your paged or non-paged memory pools as kemical's excellent article explains.
If you do the memory testing, and it passes, and you find no help with troubleshooting your software, you might consider first making sure all your personal data is backed up to external media and then using W10 built-in repair tools such as Windows reset or reinstallation and repair or reinstall your W10 and see if the problem persists. If the problem abates, this may produce a fix to your problem!

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Further, looking up your model Lenovo PC on their website, you could also use the
LENOVO RESCUE SYSTEM which will use DVD discs you can make (or did make when you first purchased the PC), or a built-in hidden rescue partition stored on the primary hard drive (as long as you didn't delete the partition or change the original hard drive out. It's always a smart idea to try and use factory rescue media to restore your PC to original operating condition. According to the specs on the Lenovo site, this PC originally came with W8.1. This means that if you use the
LENOVO RESCUE SYSTEM it will put you back onto W8.1. From there you could attempt the W10 CU (Creators Update) upgrade and try the newest version of W10 on that PC which it should support. (v1703). This may not work, as we have found the W10 Update process to be a little sketchy.

You could also visit the Microsoft website, and download the free MCT tool and do a Clean Install which we prefer. It's about the same amount of work as going back to 8.1 and then running the latest W10 update; but far more likely to work. You can get that tool from here:
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Also, I checked the Lenovo site to make sure their is driver support from the manufacturer of your PC, Lenovo, for W10 for your model computer, and there is; which mean that computer should work perfectly fine on W10!

Here's that link fyi:
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Give some thought to repairing or reinstalling your Windows, as that's often an easier way to get things working again, of course after you test your RAM memory.

If you don't take the time to test your memory, and it's really the cause of your memory problems, repairing/reinstalling W10 won't fix it.
Let us know how you get on.
Best,
<<<<BIGBEARJEDI>>>>