Black Line thru screen

Windows XP-
I downloaded 2 games which I can use offline, & when the game opens, the
screen has a 2 inch black bar across the middle of the game. This makes it
impossible to use, since the screen is blocking half the game.
Was this caused by a bad installation from the site, or some malfunction in
my computer, and how do I troubleshoot this?
--
Glenda