If I start drawing/writing then the pen often keeps writing while being lifted off and moved to the next position where I actually want it to draw. This makes the tablet completely unusable. It's similar to this question, but another type of Wacom tablet and pen.
It may help to simply remove the tip from the pen, tap the empty pen to the table a couple of times, brush dust off the tip and reinsert the tip. There was a tip remover included with my tablet, along with a selection of tips that could also be tried if a certain tip just won't work. This solved my problem.