Ungrounded power plug adaptors

From What The Wiki?!

While playing with some homebrew USB hardware I just got some small electrical shocks whenever I touched the ground connection. Since I'm connected to the power thorugh a Swiss-EU adaptor without ground connection I assume that this might be because the unconnected ground wire running along the power wires acts as a capacitor, letting some of the 230V power through. We seem to have solved the problem by using plugs without ground connecters at the other end of the cable, too.

Has anybody else experienced this?

If you use long cables and Somecountry-EU adapters without ground connection, take care, because the capacity gets higher if the cable is longer.