When I launched my theme hospital, it goes to the dosbox emulator and a pop out appeared:
DOSBox DOS Emulator has encountered a problem and needs to close. We are sorry for the inconvenience.

Anyone can help me out on this? My operating system is windowsxp

Try changing "Graphic Mode Setup" and if it doesn't work play a bit with "Settings" - you can find both shortcuts in GOG.com in Menu Start