A few things to try.
Check with your computer manufacturer for any updated sound drivers. You can also run Windows Update from the Start Menu and check if there are any new drivers found. This may help.
Make sure you have CrazyTalk Animator updated to the latest build which is version v1.1.
Try using some different MP3 file or a PCM WAV file instead just to eliminate a faulty file.
If after trying the above you still have problems then please contact Technical Support using the link below. They will be able to look at your system in greater detail and advise on how you can best resolve this issue.