my iPod nano displayed "firewire connections are not supported. to transfer songs, connect the usb cable provided" message after I was wearing it and running in a raining condition, .
googled the error, and the closest usefule tip was to lay it under sunlight for a number of hours and wait for it to be dry.
i tried it and didn't work out for me.
then a friend suggested this ISO PRO Cleaner Pump Spray i tried it on the connection port, and it worked.