It's a Trust tablet. Do all Trust tablets have problems? And as I was typing this I checked the Trust website and saw that they don't even have design tablets anymore.
I thought it might have something to do with the driver, since I've seen problems in another program, too. (Of course, it works fine with Photoshop.)
Ok, so as long as I have a Trust tablet I won't be able to use the latest Krita versions, since there'll never be a driver update... yay. And I haven't even had it long.

And thanks for the quick reply, by the way.

Yes, Trust is, I'm sorry to say, not a good brand. I'm glad they stopped making tablets, but sad that so many people bought them. I'm still hoping that a Trust tablet owner will decide to get a Wacom, Huion or Yiynova and donate their Trust tablet to the Krita project so we can finally figure out what causes the crashes