تفضل يا اخي:
nano -w /etc/default/grub
Change the GRUB_CMDLINE_LINUX_DEFAULT= parameter to: GRUB_CMDLINE_LINUX_DEFAULT="text splash vga=791 i915.modeset=1"
Press ctrl+o to save and ctrl+x to exit.
Then run "update-grub" for the changes to become permanent and you be able to startx normally without having to press tab and edit the kernel line again.