I just picked up a new laptop (Toshiba Satellite P55-A5200; on-board Intel graphics presumably HD graphics 4000 as this is a mobile i5 Ivy Bridge system) and have been getting all sorts of odd display issues. Windows 8, which was pre-installed, worked fine and without issue (aside from, y'know, being Windows 8).
Initially I found that I was unable to get the LiveCD to load when selecting "Try Ubuntu" only a black screen. The backlight was on and the laptop gave signs of life, but nothing. Eventually by adding "nomodeset" or "i915.enable=0" (presumably this was disabling the load of the i915 driver since there is no such flag) I was able to view the system as it attempted to load and would apparently lock up once x tried to start. Removing "quiet" and "splash" revealed a bit more data, but nothing conclusive. Most of the time ctrl-alt-del or pressing the power button would register so the system wasn't hard-locked. Unlike other issues I was never seeing "no monitor found" or getting a blinking cursor.
Eventually it was found that going into the "Install Ubuntu" option with "i915.enable=0" worked perfectly. All of the widgets appeared properly and I was able to install normally. Since this is essentially an X environment I thought the problem might be fixable and installed 13.04 reformatting the entire drive in the process.
Upon booting, however, the previous behavior resumed. The BIOS logo screen and grub would display properly and some text after grub would briefly flash past, but as soon as it attempted to go into graphical mode it just went to a black, backlit screen. After some work graphical Plymouth was removed and replaced with the text version and the system would boot fully. Setting CapsLock or such and then swapping between terminals showed that the switching was occurring properly. Most surprising though it was found that if an external monitor was connected to either the HDMI or VGA ports the both displays would come to life regardless of whether the external monitor was on or off. The HDMI connection initially could be removed and the laptop display would still function, but on the second time testing this it no longer worked. Connecting to VGA would still work and would leave the laptop screen on after it was disconnected. If the external monitor was connected during boot this would not work and if the system was suspended the process would need to be repeated, but would work. Either way aside from the display issue the system appears to be booting properly into X and nothing else has shown any problems.
I've been pulling my hair out over this issue for about a week with little idea what is causing it or how to fix it. I've been through just about everything else that AskUbuntu or anything else I've found online has suggested as an answer to little avail (or, at least it only got me this far). Any suggestions?