Weird Minimize/Restore Buttons

I am having a minor but annoying issue. I have two Windows XP Pro machines, both set to use the “Windows Classic Theme”. On one of the machines, the minimize and restore buttons are little arrows:

On the other machine, they are the “normal” min/restore symbols:

I know it seems minor, but I hate the little arrows! I am used to the other symbols, so it bugs me when I go to click up there and I see something different. Does anyone have any idea how I can get rid of the arrows? Thanks!