Just trying to catch an edge problem: Are you positive that the screen is black (or rather, empty)? The screen scrolls left to right as well as up and down. If you had a really long early line without breaks, it can scroll all the way to the right. If there is a subsequent screen full of shorter lines at the bottom, they will be off to the left and thus invisible. Look for horizontal scroll bars, or click in the black field and page up tot he beginning, or even select all, copy and paste into a text processor.