Simply fix: don't run dosbox full screen, run it in a window.
Open dosbox conf (start menu->dosbox->configuration->edit configuration)
Look under header [SDL] and set
fullscreen=false
fulldouble=false
fullresolution=original
windowresolution=1024x768
Something in those params, try other values if they doesn't suit you.
Read this tutorial from Japo to learn more:
http://www.abandonia.com/vbullet/showthread.php?t=17499
And read the dosbox readme.
BTW, Norton is indeed useful, but optional, dosbox can work perfectly without it.