As long as you are only copying new lines of code into your old (copied?) code, the problems will persist!
As MattP (Post#10) and I(Post#6) have stated you need to run the code to generate the list only once! since you are doing that each time you click your Button1 it won't change!
Remember your list holding all the numbers is alled "list", why are you using a new one called "ListBox1" now?