It sounds like something is wrong with the screen. I just turned mine on to check, and with the brightness all the way up the screen should be pretty much white, and with it all the way down the screen should be black, with only the brightest colors visible at all.
What kind of power are you running? On mine the screen goes nuts right before the batteries die. You have to keep adjusting it darker and darker, until finally you have it set to the highest darkness and just keeps getting lighter and lighter.
Perhaps someone else can chime in here, the only thing in the Express I know how to fix is the sound, I've never messed with the screen.