Lcd screen works in safe mode not in normal

Hello,

My computer works just fine in safe mode but when I start it in normal mode I hear it start up get a screen has lines at the top and then is goes black. In safe mode it's fine and starts right up.
Any ideas how I can fix this?
I have an acer aspire 5100 running vista. It has had screen issues before where if I move the screen it will flicker and go black, but without moving the screen at all it works in safe mode and not in normal.