Window Minimizes on its on

I have only been working with Windows Vista for about a month, but have an
unusual problem. Whenever I click on the right side arrow of the open window
to scan up or down on the page, my window will minimize. I have tested it on
my husband's laptop and found the same problem. If the window does not
minimize because it is a pop-up, it will get larger or smaller when I click
on an area of the window. It is becoming annoying as this will happen in the
middle of an email or reading a webpage.
Has anyone else experienced this issue or is there some type of adjustment I
can make to the window size to stop this problem?
Thanks for any assistance in the matter,