Why do I have to hit SHIFT+ESC?

I am fairly new to Win7... loved XP... now in all the places I used to hit ESC to do things... (like undo in BLENDER or STOP in IE) now I have to hit SHIFT+ESC to do the same things... and I dont know why... but it is annoying... I want my NORMAL ESC functions back? anyone know why it is doing this and/or how to change it back?