Ctrl+X closes windows - and then some...

I'll be the first to admit I'm probably not the best person to try building computers, but I have - more than a few times and I guess I've been lucky until now. My ASUS Maximus VII Hero motherboard went belly up recently, so I went with the Maximus VIII this time and it's been anything but happy since. For now I'll ignore the slow boots even though I'm running an SDD boot drive and focus on this cut and paste problem.

Any time I go to rename a file by trying to cut a portion of the file name with the CTRL+X keyboard shortcut, it closes the window. CTRL+X also closes my browser windows. And now I've found that using the same shortcut when editing text in an RTF file it not only closes the file, it makes it so I can't open it from the original location. I can copy it to another location and open it just fine. But clicking on the original does nothing. This is just too bizarre and, of course, Internet searches have turned up zero on the issue. That's why I'm here, hoping someone has seen anything like this and knows what to do about it.

Basic system specs have been filled in.

Shortcuts aren't the same for all languages. What is the windows language ?

That was the first thing I suspected might be wrong, but it's set at English (U.S.).

I'm not referring to the keyboard layout. I'm referring to Windows language.

I'd checked both the Windows Language and the keyboard layout - both English U.S.
I'll also add that I've tried two other keyboards and both still duplicate this glitch.

Ok, I suppose that the computer has always been yours and you didn't install any shortcut program.
At Control Panel\All Control Panel Items\Programs and Features, look for any strange program.
Also some games can change / create shortcuts.

I appreciate your replies. This is very frustrating. This wasn't happening for the first couple of weeks with the new build and I haven't installed anything that wasn't on previous builds. It just came out of nowhere. System restore didn't fix the problem nor did sfc /scannow. Virus and Malwarebytes scans didn't turn anything up. I even tried a registry repair with Glary Utilities. It's still a mess.

Sorry, can't help you further.

Still hoping for a miracle solution before I do a clean install...
Checking to see if the closing window glitch is still happening, I opened a Notepad, typed a few characters, highlighted them with the mouse and, sure enough, Ctrl+X still closes it. But now I get to add that Ctrl+z opens previously closed Notepads. What IS this??? (Other than maddening).

Seems to be very strange.
From How do I change the Windows 7 Keyboard Shortcuts - Microsoft Community
" you can not use windows default shortcuts to other applications , unless the application has been designed accordingly. you may have to use other shortcuts."

Did you scan the computer with a antivirus?
I like this anti malware SUPERAntiSpyware - Downloading File