first time asking something in here, usually I search a lot before post but this time I've not found anything related to my problem
I've been trying to change my login screen background and after lots of trials and errors I've finnaly did it, but suddenly a annoying problem appeared, everytime I boot-up the system, at the login screen half of the screen (almost half) is black, like if my screen resolution was wrong and I don't know how to fix it, can somebody help me please?
Ubuntu 14.04 LTS
edit.: missing Ubuntu version