Why can't I use my touchpad and the keyboard simultaneously?

I’m sure this isn’t typical on most laptops but mine (if it is the laptop and not the OS) won’t allow me to use the touchpad if I have a key held down. While this is only a problem when I’m gaming and without a mouse (a rare occurrence), I would like to know if there’s a solution. I’m using Windows 7 if that helps.

Thanks in advance.