My neighbour has an Amilo 2636 (Vista Home Premium) but when he plugs his TV/monitor into the HDMI port the laptop screen goes black and nothing shows on the external display either.
Fn+F10 doesn't help, although the black screen looks vaguely lighter when you toggle through as if it may be trying to display something.
All the drivers are up-to-date, all Windows Vista updates applied and the system is clean of viruses and spyware.
Any ideas greatly appreciated.