my until now perfectly working (1 week old) Duemilanove started to not work properly out of nowhere. When I power it on, it works for some minutes and then shuts down. I can't upload anything or get any response, until unpower it for some hours(!) and then it works again for some minutes.
Power supply and Serial-USB Chip work all the time. Tested only wih Pin13 onbaord LED, nothing else connected.