The first thing you may want to try is to ensure that your OS is up to date on all system updates. Assuming you're using Windows 7, navigate your way to Action Center by going to:
Start -> Control Panel -> System and Security -> Action Center
Select on the option (On the bottom-left hand corner) that says "Windows Update". It will show you any mandatory or optional updates that are available. As the name entails for you, an "optional" update is not necessary. A mandatory (or important) update is necessary in order to keep all of your system's applications and services running properly. Restart your computer after all updates are installed.
If this does not work, try this: Remove your sound card and delete any audio drivers that may already be installed. This means checking to ensure that there aren't any previous drivers installed from any previous cards, to include your motherboard. Once this is done, insert the disc into the optical drive and install the drivers directly from the disc. Once this is done, turn off the computer, install the sound card, and boot it up again.
If it is still giving you issues after this, go into Device Manager. Assuming you're using Windows 7, you can get there by going to:
Start -> Right-click "Computer" -> Properties -> Device Manager
Find your audio device (Under "Sound, video and game controllers") and right-click the device. Select "Update Driver Software" and elect to search the internet for available updates. Let it run. If there are any updates to your sound device, install them and restart your computer.
Let me know if any of these steps fixes your problem! If it doesn't work we'll try something else to get it fixed.