I am experiencing a weird problem with my dell latitude laptop. I installed debian amd64 once with gnome and after grub it echoes the following message:

Unknown controller version (2). You may experience  problems.

and after the /dev procedure my screen (16:9) goes black.

After that I tried to reinstalled debian without gnome and I booted to shell. From there I installed manually (apt-get) gnome and started gdm3 and I my screen was ok, but after I did a reboot the same problem happened. Also, when I boot with an external VGA monitor, the external one looks ok but the laptop screen is still black.

output of lspci | grep -i vga

    00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)
Also, I realized the following strange thing. If I boot without the external monitor plugged, I get the usual black screen and If I wait and understand that I am in the login screen and at this time I plug the external monitor, then miraculously my laptop screen works fine (even if I pull out the monitor)!!! But later on if I close the laptop lid and open it again, then again ... black screen but if I plug the external monitor, the laptop screen is ok again!!! This thing drives me mad...

any help would be appreciated!
Thx in advance!