If detects that any part of a DVI page
is off the paper then it will beep and show a full view.
TEX will often catch these errors
(e.g., overfull \hbox or \vbox)
but there are quite a few situations where it can't.
TEX really has no idea about what paper size you intend to print its pages on.
If you're sure the problem isn't in your input file then
use the ``Page Info'' item to see what thinks the paper dimensions are.
You could have forgotten to reset the landscape option or you might have made
a mistake when changing the paper dimensions in a configuration file.