When trying to start Ubuntu from my USB key in UEFI mode (it works in Legacy mode, but I have to keep Windows) on a Dell Inspiron 15z , Grub starts, but when I choose any option, I get a black screen and my USB key stop teling me it is being read. EDIT: when using the legacy mode and trying to install Ubuntu, I get a blank partition table with Ubiquity… … and a very strange partition table from GParted (I have a hybrid 32Go SSD + 500Go HDD disk) :