I have the following phenomenon:
I shutdown my PC and Blinkstick keeps the last light color (green for example; Blinkstick is connected to a monitor USB hub). If I start the PC I cannot reset the light by software. So the old light color and the new light color are now mixed. (old green light, new color is blue = yellow).
Is there a way to avoid this? At the moment I can only plug the device off and reconnect it.
What OS and software are you using to control BlinkStick?
Win7 64bit and NotifierLight 
You can get a notification that windows is shutting down and turn off BlinkStick just before application is closed.
Yeah I know but thats not the point. I cannot reset the color. I send color black but the color is still green. I send blue and the light is yellow… I have to plug it off to reset.
So BlinkStick ignores any requests to change the color after reboot?
Yes, thats what I meant
Which of the devices is it?
It is a Blinkstick square in mode 3
Does it happen in mode 2?
Cannot reproduce it at the moment. But it seems it does not have to do with the shutdown. My colleagues say that sometimes during the day the light stops working until they “replug” the device. I think I need to do a bit more research to give you more details…