As per the error you're receiving, I recommend running your files through Codec Config to set up the codecs for E-Prime to use. For more information about Codec Config, please see 3162 - FEATURE: CodecConfig provides ability to choose codecs used for Movie and Sound rendering. The Knowledge Base topic contains a video that explains Codec Config in great detail. Note that to maximize the functionality of both E-Prime and Codec Config, you should install a comprehensive codec package such as K-Lite Mega Codec Pack and the latest version of DivX. After installing the appropriate codecs, open Codec Config through the Start menu or through E-Studio's Tools menu. Select "Create Default Mappings" from the Codec Config Tools menu, then click the first option button. This will set up the mappings that are most likely to work on your machine. Next, select Render File... from the File menu, find one of your audio files and click Open. If you receive errors, please try rendering it again until you see only warnings or success.
I also recommend importing your audio file(s) into Graph-Studio-Next. This is a program that essentially shows the 'flow' of an audio/video file, and can help determine exactly what codecs are needed and are used in playback and output. I also recommending viewing 3162 - FEATURE: CodecConfig provides ability to choose codecs used for Movie and Sound rendering once again. This video demonstrating Codec Config has an excellent tutorial on using Graph-Studio-Next for use with CodecConfig.
I also recommend verifying that you have the most up-to-date version of your audio drivers installed. To do this, first navigate to your Start menu > Run > dxdiag.exe ... This will start the DirectX Diagnostic Tool. This is a diagnostics tool used to test DirectX functionality and troubleshoot video- or sound-related hardware problems Next, click the 'Sound' tab. This will present you with information regarding the manufacturer of the hardware as well as the actual device. Notice on the left of this screen the 'Drivers' section. This shows information regarding the drivers used for this hardware, as well as the date they were last updated. Take note of all of this information.