Have recently installed Ubuntu 12.04.2 LTS by USB on my newly built custom pc and I have run into a problem during installation with the error saying "No root file system is defined." My pc speculations: AMD Phenom x4 955 Black Edition ASRock 960GM/U3S3 FX Micro ATX AM3+ Motherboard Mushkin Redline 8GB (2x4GB) DDR3-1866 Memory Seagate Barracuda 1.5TB 3.5" 7200RPM Internal Hard Drive XFX Radeon HD 7850 1GB Video Card XFX 550W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply Everything is new.