My friends and I occasionally have this problem so I’ve taught them this simple method that takes less than a minute as opposed to waiting several for your computer to restart(especially if it’s slow).
What’s great about this method is that sometimes restarting your computer wont fix the problem, but this usually will.
MAKE SURE YOU CLOSE ALL YOUR ART APPS.
This is important, otherwise the changes wont take effect. If it doesn’t work the first time, try again, sometimes it takes restarting it more than once.
For Windows 8, search for “services.msc” in your apps and click on the result. Continue from there!
Now go draw, babies!