Are you plugging and unplugging the USB dongle, or does it stay plugged in all the time?
Please run lsusb
in a terminal and post the results, pointing out which device is the dongle.
Have you also tried restarting the bluetooth daemon from e17 by doing the following?su -
but now suddenly i cant launch the bluetooth manager anymore from E17!!!
OK, the daemon is probably running, but the manager won't start. Try this: restart e17 by doing the three key combination of Ctrl-Alt-End. It will take a couple of seconds for e17 to restart. Or, you can restart e17 from the menu at Main > Enlightenment > Restart. See if the bluetooth manager will start after that.