Hi, I have a Surface Pro 4, and one of the main reasons I have one is because I create a lot of digital art. I got it almost 2 years ago and it works fine, no problems. I got Paint Tool SAI 2 for it pretty much as soon as I got it, which has also worked fine with no problems, it's been great. All of a sudden the other day, the brush wasn't working properly. The pen was too slow, slower than how I was moving the actual surface pen, and the strokes would go thin when I wasn't pressing lightly out of nowhere. I used my pen on other things like other programs like discord and chrome, just click around and touching things and it worked fine as it always does, but I tried re-calibrating my pen a couple of times anyway, but it didn't solve the issue with Paint Tool SAI. I restarted my computer, it didn't do anything. Then, a new problem arrived. When I'd hover my pen over the screen when I was on SAI, the cursor would shake and flash rapidly, and if I tried moving the canvas using the window in the corner (where you see a small full preview of the canvas), SAI would essentially go crazy and move around by itself, the canvas moving around randomly. I cleaned my screen with special screen wipes just in case, it didn't make a difference, and nothing else was having weird issues like SAI was. The pen and touch functions worked just as fine on every other program and in general, the problem is only with SAI. I tried uninstalling and reinstalling SAI, it made no difference. I tried troubleshooting, it did nothing. I was thinking maybe it's time to move onto another program, like Clip Studio Paint, since it's much better than SAI, but I don't have the funds right now, so SAI is all I have at the moment. I really don't know what to do, if anyone knows anything or can help me I'd be really grateful.