Errors when opening/saving Office files, how to repair?

Hello all,

Office decided to stop working last night. Everytime I save/rename a document I've been working on I get an error.
Saving an Excel document I've been working on: "Your changes could not be saved to FILE NAME because of because of sharing violation"
When I click OK on that: "Your changes could not be saved to FILE NAME but were saved to a temporary document name BLABLA. Close the existing document, then open the temporary document and save it under a new name"
When I click OK on that: "The file you are trying to open, BLABLA, is in a different format than specified by file extension. Verify that the file is not corrupted and is from a trusted source before opening the file. Do you want to open the file now?" --> I click on no coz it goes round in circles.
When renaming an Excel document: "INVALID MS-DOS FUNCTION"

Saving a Word document I've been working on, it opens the Save As function.
When say overwrite the existing document: "Word cannot complete the save due to a file permission error."
When renaming a Word document: "INVALID MS-DOS FUNCTION"

I figured I'd uninstall & reinstall Office. It made things worse..
When I try to open a document (any) it says: "The program can't start because MSVCR80.dll is missing from your computer. Try reinstalling the program to fix the problem" Followed by: "There was a problem sending the command to the program". Same happens when I try to open a document from my external backup.

On a different laptop it will open the documents from my external backup, so it's the program not the documents themselves.

HELP!! What do I do?

Microsoft Office Enterprise 2007

I've since found that it is not only Office acting up though...
When renaming any file or folder I get the warning: "INVALID MS-DOS FUNCTION"
Dragging a file from one folder to another, I get the same. I can copy/paste to another folder though.

A bit of a panic when the laptop froze completely when I tried renaming a folder. Screen turned black, showing the mouse pointer but nothing more. Forced a shut down and it restarted OK after that.

Now doing a backup to an external disk so I have the latest versions of my documents, pictures, etc.

My laptop is a Toshiba with Windows 10, 64bit (had it for just over 2months!)

Finding out more and more anomalies...

When from C I click on Users, I get this -looks different than normal...
When from Users I click to Evelyn, I get this -which looks dramatically different from what it should look like...

Is it a system/OS issue? Then I should repost elsewhere in the forum...
Also wondering: I installed Malwarebytes and SUPERAntiSpyware on advice of forum members about a previous issue. Could running these somehow have had this effect on my OS?

I reposted elsewhere on the forum, I believe it's an OS problem not Office problem since it's not limited to Office.
Thanks!