Have a work PC that had not been used for about 2 months. Turned it on got message that hard drive was not found. Opened up PC to check that nothing had become loose or dusty. Replugged in power supply and found that the back of the tower was conductive (PC powered off). unplugged power supply and there was no conductivity. Checked the power strip and all was ok. Replaced the power supply cord PC returned to conductive.