I have an R25 with 4gb ram running XP with the latest Wacom drivers. Yesterday I noticed that my stylus would stop responding in sketchbook completely at random kind of like a pen running out of ink. As soon as I lift the pen and start drawing again it will work, but then stop at random again, although not on every stroke and not at the same point. My guess is that another application is interrupting the process and taking focus from sketchbook, but I'm not seeing anything unusual in the task manager. I tried in photoshop and it's fine, so possibly something Open GL related? I have no idea...any suggestions would be great-thanks in advance!