Are you running any antivirus? (We usually don't have this problem but it is changing all the time.)

@who-cares yes I have done something like this in the next build but didn't want to update people twice in one week

I've turned grayscale on to try it, but now I can't turn it off again. I need to see the diffrerent colours on my calendar for example. I've tried WINDOWS+END again, hoping it workd in reverse, but it doesn't. Please help me f.lux.

Not sure why nobody replied to this. Yes, it will interfere with color correction work. Have Photoshop open, then right click the f.lux tray icon, click Disable > when using Photoshop. The option might be in a different spot in older versions so make sure you're up to date.

Oh, yeah, I forgot to mention that I tried f.lux's software mouse cursor setting. I tried everything in the f.lux options. I'm using f.lux 4.78 and I don't plan to get a newer version until this is fixed!

Note: for me, this has nothing to do with this new Grayscale mode. I experienced this bug without even using that mode.

It's great isn't it? Unfortunatly I'm on a not so powerful pc at work and running windows 7.
Because aero is then needed the pc (well graphics drive) becomes very slow.

For your phone you can use Twilight. It's free and I just toggle it on/off when I want the blue out.

I am not experiencing this. There are two things I can recommend:

Try updating your graphic card drivers Go into options and select Very Fast: Gaming for transitions. This should give you the minimum transition time, so if you're having issues with transitions it should now just last a second or two and not a few minutes.