I'm not sure if the GMA 4500 video chip is supported by Genode, if you
have an old VESA video card lying around, you might have some more luck
on the Dell.

It is an integrated Intel 82Q963/Q965.

I have tried with a radeon 7200 (R100 PCI card)... my monitor complains on resolution (Linux too), and reboot like before.

I have tried with a GT 400 card, it seems to reboot faster (like puting the computer like in sleep before rebooting).

So it's probably linked to the computer itself rather than to the graphic card.