Had the same problem on Windows 7 and solved it like this:
1) Navigate to C:\Users\%USERNAME%\AppData\Local\EA Games\Dead Space 3\system.txt
2) Open system.txt and find the following lines: Window.Height = 720 and Window.Width = 1280; you need to to edit those numbers according to your screen resolution. Mine is 1920 x 1080, so I edited the lines like this: Window.Height = 1080 and Window.Width = 1920
3) save and close system.txt and try to launch the game: it worked for me, hope it works for you too!
