I think this might help you. My mate had the same problem and i resolved it like this.
Use the following steps to install the sound driver from the Drivers CD, and then change the Creative Sound Blaster AudioPCI 128D Output Mode from Autosense to Digital.
To install the sound driver:
Place the Drivers CD into the CD/DVD drive. The CD starts automatically when Autorun is enabled.
Note: If the CD does not start automatically, click Start, and then click Run. In the Run dialog box, in the Open text box, type: D:Runmenu.exe (where D is the drive letter of the CD/DVD drive). COK.
In the System Restoration Kit window, click Manual Installation.
In the Sound video and game controllers area, click Creative Sound Blaster Audio PCI 128D, and then click Install.
In the SBSetup dialog box, verify that Install Software is selected, and then click Next.
Files copy.
In the SBSetup dialog box, click Finish.
Click Start, and then click Turn Off Computer. In the Turn Off Computer window, click Restart.
To set the output to digital:
Open Control Panel.
If you are using the Windows XP default Start menu, click Start, and then click Control Panel.
If you are using the classic Start menu, click Start, point to Settings, and then click Control Panel.
In Control Panel, open Sounds, Speech, and Audio Devices.
If the computer is in Category View, click Sounds, Speech, and Audio Devices, and then click Sounds and Audio Devices.
If the computer is in Classic View, double-click the Sounds and Audio Devices icon.
In the Sounds and Audio Devices Properties dialog box, click the Hardware tab.
On the Hardware tab, click Creative Sound Blaster AudioPCI 128D (WDM), and then click Properties.
In the Creative Sound Blaster AudioPCI 128D (WDM) Properties dialog box, click the Settings tab.
On the Settings tab, in the Output Mode section, click Digital, and then OK.
In the Sounds and Audio Devices Properties dialog box, click OK