A device is the hardware inside your laptop and the driver is software that makes it work. Go to Contol Panel>System>Harware>Device Manager. You should have a list of the hardware in your laptop with little + signs beside each one. At the bottom there should be Sound, video and Game Controllers. If any have yellow exclamation marks beside them they need their driver re-installed.
Ok. In Device Manager > Sound Video Game Controllers if you right click on Realtek AC97 select Properties and make sure Use this device is selected at the bottom. Then click Driver tab, it should tell you what driver it is using. If you installed the driver from Acer it should be that one. Or you can click Update driver and let it search for the best driver. Let it search the internet as well.