

See the error message like in the question.After you disable both, problem goes away. It appears that "PrintScreen" was taken by OneDrive and "Ctrl + PrintScreen" - by DropBox. Initially, Greenshot complained about "PrintScreen" and "Ctrl + PrintScreen" for me.

In case you want to use Greenshot but still don't want to turn off that specific feature of OneNote or Dropbox, another alternative would be to change Greenshot's hotkey, you can easily do so in Greenshot's settings dialog. Configure them not to use the PrntScreen hotkey, and restart Greenshot. If you want Greenshot to work with the PrntScreen, you need to find out which program is blocking the hotkey, it is most likely either OneNote or DropBox. Greenshot cannot register the desired hotykey (PrntScreen) if another program has already registered it, that's why it gives you that warning message. Select No and the key will be free for Greenshot. On a new PC, press printscreen and the first time OneDrive pops up and offers you to save screenshots.
