inspiron 5000 volume control

I got a the inspiron 5000 laptop with windows 98 on it (not SE) and it worked okay.  But I decided to upgrade the laptop to  windows xp.  For the most part it works great and it has all the features I want, but for one thing.

This specific laptop has two buttons on the side for volume control.  That way I don't have to open volume control in windows, I can just press the two buttons and volume goes up or down.  Press them both at the same time and it mutes, it was great.

But ever since I upgraded it, Those buttons don't work.   The volume still works, I just can't control it with those buttons.  I'm guessing it's a driver problem, but the computer says all drivers are working fine.  I'm not even sure what that device is called, so I don't know what kind of driver to search for online if any drivers need to be updated.

Does anybody know what I can do about this?