I successfully installed 14.04 along with my pre-installed Win8.1. Ubuntu 14.04 was working fine, but after I restarted to complete the upgraded to 14.10 the screen is just blank/black with a blinking underline. The boot menu does appear before getting to the blank/black screen, so I am able to boot into Windows8.1
When I tried booting to Ubuntu 14.1 again, the blank/black screen is all I get. When I press the power button even just one second I see for one second the text "Ubuntu" with the usual progressing dots underneath it, and then the computer shuts down. Do I have to re-install Ubuntu 14.04, or is there a fix to make 14.1 work? If I have to revert back to 14.04, should I use my USB Ubuntu 14.04 install flash drive?