An Arduino does not withstand 9V on Vcc, rated max. is 5.5V.
Mainland Europe is 220V, UK 240V, these small differences in voltage and frequencyshouldn't matter at all to a universal switch-mode power supply... It might have beenpoorly conditioned power (industrial, agricultural - UPS's are recommended in such harshenvironments.) Or a cheap sub-standard power supply unit (out of spec but holdingout at 110V apparently fine).