Volume indicator gone?

After recovering from a virus, I noticed that the green volume display indicator bars that move when you turn up or down the volume are gone. I might have adjusted some settings that messed it up too, but do you know how I can get the volume display back?

I have a lenovo thinkpad, running windows XP. Thank you!

I figured out at least one way to fix this - I went to IBM's website and downloaded the hotkey driver for my particular model, and it fixed the problem. I think there has to be a way to fix it by messing with the controls and settings on my computer, but downloading the hotkey driver also worked!