I’m having this problem with my cintiq where the brush skips off the screen and makes an X on the model, never had this problem in zbrush 3 but now i’m using zbrush 4 and it’s making my cintiq pretty much useless 
any idea what’s up?
i never had that problem, but if you update the drivers, keep the following in mind:
(i had to reinstall the wacom driver recently and had quite some troubles…)
it turned out that i had to reinstall the old driver before i installed the new one, then everything worked fine
maybe this hint could save you some time 
I get this once in a while with mine too. I just undo it and I’m fine for a while. I have no solution just affirming the issue.