Pen keeps freezing and buttons won't work

I've had my H950P tablet since January, and it's worked perfectly until the last few days. I'll make a brushstroke, but it's like the pen freezes halfway through so there's a giant gap, then when I press undo (I've customised my pens buttons to undo and erase) the cursor freezes in place until I let go and nothing happens. Same problem with the eraser button. I have the same custom keys on the actual tablet itself and the keyboard, both work perfectly fine. I've uninstalled the driver, installed the newest one, restarted the PC, done everything I can find but nothing is working, please help.