If you are experiencing difficulties in listening to .AVI files, you need to download the 'Sound Fix' patch from the link shown below and follow the steps provided below to install it.
How to download and install the fix:
1. Before installing the patch,back up your current LNL.DLL by copying this file to a different directory.
The default location for the ToolBook system files is :
c:\mtb40:for ToolBook 4.
2. Download the file soundfix.exe(~98K) to a temporary directory on your computer.
ToolBook 4 : ftp://ftp.click2learn.com/pub/tb/mtb4x/updates/soundfix.exe