tell mplayer which sound device to use

mplayer -ao oss:/dev/dsp *.mp3
mplayer -ao alsa:device=hw=0.0 *.mp3


or

mplayer -ao oss:/dev/dsp1 *.mp3
mplayer -ao alsa:device=hw=1.0 *.mp3

wacom bamboo stops working after unplugging

to solve this (to get it working as a graphic tablet again without restarting X) just switch from X11 to Console (press Ctrl + Alt + F1 together then release them) and then switch back to X11 (press Ctrl + Alt + F7 together then release them).
Then the graphic tablet works as before unplugging!