Dos Programs Stopped Working in Windows?

[Necrosaro420]

I run Windows XP Pro edition. For some reason one day after a reboot, all of my dos programs want to run full screen, and they will not run in small screen mode now. Also an emulator I am running stopped working as well. Any clue on what this could be? Thanks!

 

[LiLithTecH]

Have you checked the EVENT Log for any clues?

(Start \ Settings \ Control Panel \ Administrative Tools \ Event Viewer \ Applications)

 

[GeekDrew]

Tried pressing <Alt>+<Enter> to switch between normal and fullscreen mode?