What is the DVR front panel?Have you ruled out the possibility that this is due to the remote control for some other device in the room being used?
The Hikvision NVRs and DVRs accept commands from an infra-red remote control.
Some are supplied with a remote, some are not.
It can happen that the infra-red signal from the remote control for another device e.g. your TV is received by the DVR/NVR but it cannot do what it is being asked to do.
Get a feel for whether it corresponds.
Put something in front of the DVR/NVR's front panel that will block any spurious remote control signals for a day or so and see whether this problem disappears.
What I have picked up is that this error seems to only be popping up when my TV is on. I turned my TV off for an hour, and the popup didnt appear. I turned my TV back on and after a few seconds, this popup came back up.I can't be sure where the infra-red remote receiver is on your model, so I'd suggest that you block the whole front face of your DVR - just put a couple of books across its face to test whether the issue goes away.