I keep getting logged out when navigate the backend

[Stephen-FFC]

I'm having a recurring problem that's not going away, and I think it's related to cookies.

I've got a fresh, clean installation of PS without any 3rd party themes installed. When I work in the backend, sometimes when I click on a link down the left, I get redirected to the login screen as i"ve been forcibly logged out. I login again and sometimes I remain on the login screen, and sometimes I'm taken to the page I was previously on. Click the same link and this logout event happens again.

However, If I clear my cache, login and click that link again, everything works fine. An hour or two later, I get the same loop happening again. (Not necessarily from clicking the same link. It seems quite random as to which link gets caught up in this login loop).

I'm primarily using Chrome on Windows, but I've also had it happen once or twice in Firefox as well, so I don't think it's the browser.