Almost every time I copy images in paint.net my copy & paste functionality stops working in Windows 10 (latest build). After much trial and error, I have narrowed it down to paint.net following these steps:
1. Open a fairly large image (e.g., 1000x1000)
2. Select all and press Ctrl+C to copy the image
3. Paste the image somewhere else
4. Repeat steps 1-3, copying different images
Eventually you will get this error, after which copy & paste stops working in Windows:
In order to fix this, I have to log out and log back in.