When you play back your project in CrazyTalk does it play as expected?If it is only on export that things go out of sync then try changing video formats to WMV to test if the issue is with AVI only. Is the problem still the same?
Likewise try reducing your output resolution. If you are trying to export high resolution uncompressed AVI video then this can cause sync problems. Choose a low resolution such as 640 x 480 etc. and see if the problem continues.
Also do check that you have the latest sound and graphics drivers installed. Having outdated drivers can cause problems like these.