A hair dryer has a diode in it for the "LOW" setting, so what its saying (Fault 05) is that there is an unbalanced load on it if you imagine a sine wave power graph, power would normally be used on both the upper and lower portion of the sine wave, but this hair dryer breaks those rules by inserting a diode as a cheap and easy way to limit the power to the heating element but only conducting power on half the sine wave. hence the fault code.
If you had some other loads on there too, along with the H Dryer , you may be able to get away with it, or use the dryer on FULL power.
Ian