Hi. First and foremost, do you use ChibiPaint, or ChickenPaint (note: V2 of ChickenPaint is currently experimental, and your problems could be arising from that).
Have you tried updating Java, or installing the JTablet extension? These aren’t necessarily needed anymore (due to the addition of ChickenPaint), but they may provide a solution. If that doesn’t work, then there’s no harm in trying the basic ‘uninstall-and-reinstall-drivers’.
It might also help to give more information on the exact model of your tablet. Some browsers do not recognize certain brands of tablets, which could be your issue.