I am connecting the projector using the VGA input of the projector and the VGA output of the laptop, which I assume comes directly from the graphics card and I am using a male-male VGA cable. The funny thing is that this used to work perfectly a few days ago and it even detected the projector as "EPSON(seiko)" or something like this.
I tested the projector with windows vista and I managed to set the resolution to e.g. 1280x720 successfully, I suppose that the projector and the cable are still working.
Thank you for your quick replies and your help