Hello and welcome to the toughest question on the internet! Brought to you today by this machine: Toshiba Qosmio x505-q830 core i7 720qm, 4gb DDR3, 320GB HDD, nVidia GTS 250M.
I have tried installing Ubuntu 12.04 desktop 64bit and Linux Mint 16 Petra w/ Cinnamon both produced same results. I am not dual-booting this with anything else, attempting to use a single OS (linux).
In order to run the liveUSB i have to boot with "nomodeset", once booted into the liveUSB install runs perfect and asks for reboot. I reboot, add nomodeset to grub and go from there. Do a update && upgrade. Install "Additional drivers" for nvidia (tried both version 331 and 309), after install i am asked to reboot, i reboot this time without nomodeset and i get a black screen with no activity. Force a shutdown, try to reboot with "nomodeset" and same frozen deal. All of the above repeat with identical results and error messages across ubuntu and linux mint. Below are a few links that may help:
dmesg, syslog, kern, xorg.0 log files -
system specs as per Toshiba and verified by me -
BIOS version currently installed is latest available from Toshiba Support ( v 2.90 )