When I launch the game from my girlfriend laptop the screen is all green but you can hear the music. Instead on my pc it works fine in everything. We have both recent pc with Windows 7 64bit.

Any idea?

It's normal for different machines to require different program settings, even if they technically run the same OS. Unless they're completely identical in terms of hardware and drivers, maybe?

There should be a link to the DOSBox configuration tool in the game's start menu folder, called Graphic Mode Setup or something similar. Launch that and try to experiment with the "Graphic mode" setting. If you get any usual "application may be installed incorrectly" Windows messages in the process, ignore them. Also, if the game is installed into Program Files (never a good idea), it might require admin rights for the changes to apply.