interesting! don't know what is the use, but msie create a native built-in object named as item, don't know what it contain. so, when you create the variable item as global in the event onclick, msie will throw an error because it seem the object is read-only. the interesting part is if you define the variable with var statement in the global scope, msie don't throw error. but if you do the variable as global (i.e. without the var statement) in the global scope, error is throw.