We started backing off polling (checking) in the background and did it only sometimes, and we thought we had kept enough of the polling to fix it - and actually, v4 works with newer drivers.

My recommendation is either to update your drivers to something more recent than 2010 or to install our old version instead, which will still keep polling all the time:

https://justgetflux.com/flux-setup3.exe

In response to "How long does this problem last?" -- I don't give it a chance to see how long it lasts, I just immediately reset it to what I want. No worries.

I don't mind having to now change 3 slider bars instead of one -- that is not the question. The issue is --

Why, when I have all 3 bars set to the same thing, is there an abrupt color change 7.5 hours before "wake up" time? What setting is it changing to, if not one of the 3 slider bars I've chosen (which are all set to the same thing, so I shouldn't see any change)?

https://www.intel.com/content/www/us/en/support/graphics-drivers/graphics-for-2nd-generation-intel-processors/intel-hd-graphics-3000.html

I already had a slight troubles with the v3 when upon waking up (actually only the screen was turned off), the screen would quickly revert to non-flux settings for a few seconds.
It went like this : black screen -> flux-enabled screen (2 seconds) -> flux-disabled screen (2 secs.) -> flux-enabled screen (permanent).
But that was a minor disagreement so I just lived with it.

Now with the v4 it "flux disabled" sequence comes right after the black screen, and does not automatically reverts to "flux enabled". I have to do it manually. And that's not pleasant at all when my normal setting at night is Ember.

OS : Windows 7 SP1.
Graphics : integrated Intel HD Graphics 3000, driver version 8.15.10.2476

@Spede-Pasanen are you seeing problems when the machine wakes up? We had a long beta hoping to fix all of these cases. Can you post your OS version and driver version, if you can see it?

My f.lux seems to have automatically updated to v4 yesterday :

Good thing : I can finally change the colour temperature to the reddest setting before the sun has set.

Bad thing : it bugs. I've let my computer unattended twice (before & after sunset), and twice I found it with a blindingly bright screen. I thought f.lux had crashed, but no, I somehow had to manually right click on the taskbar icon and change the colour temperature.
I don't know if and how it's related to Windows' standby mode, but what I do know is that none of this happened with the previous version of f.lux. And I haven't changed any Windows setting in the meantime. It can only come from f.lux.

So please look at how v3 worked and just copy that into v4. The fact that it randomly exits the specified temp colours is a big issue.

Thank you in advance.