"Write Error" when saving

So I recently bought a new PC. I’m not used to windows, I’ve never run across this problem on a mac.
When I try to save my file, often I’ll get this error message

Write error: Unable to create backup file
The scene could not be saved because of a network or disk error (permissions or other)

The folder says I have read and write permissions. There’s an option for Full permissions, but that doesn’t seem to matter.

I can save a new version and then start saving with that version. But when I go back to the previous version with the error message, I still get the error. Seems weird…
Anyone know what’s going on with this?