I can't remember if I have a sound card or if I have integrated sound. DXDiag tells me that I have 'SoundMAX HD Audio,' which I'm not sure some wing of the Creative company. I found no Creative folder in my Program Files folder either. Also, I'm running an ASUS motherboard.
Under the Advanced options in the Volume tab for Sounds and Audio Devices Properties, the mode is set to "Desktop Stereo Speakers." I have 2 desktop speakers and 1 subwoofer, if the presence of the subwoofer makes any difference.
EDIT: I just remembered that not too long ago, a friend of mine brought his computer to my house, but never brought any speakers along. I made the mistake of taking the audio jack out of my speakers, rather than my computer, and plugging it into his PC, so my PC was sending sound to him, and his PC was sending sound to mine. I don't know if this may have damaged anything, but I don't see how something like this could cause only some sounds to mess up.