Hi cowboy2009,
Can you try playing a few of the mp3's using any media player you have (Windows Media Player, VLC, etc.)? You can access your Little Reader Media Library by going to Start > All Programs > BrillKids > Little Reader > Open Media Library. All mp3 files from the Aesop's Fables digital files have "bk aesops" in their filenames so you may do a file search for those too.
In case you were not able to download the Aesop's Vol. 1 file completely, it may be best to try re-downloading and import the file again. Simply visit the
My Files > Redeemed Digital Files section of your Account Management page and you can download the file from there (no need to enter the redemption code again).
About the "sound repeated," please describe what is happening in more detail, and do make sure that you didn't repeat the slide during playback (this will happen if you accidentally clicked on your mouse-wheel or pressed the Down Arrow on your keyboard).
Also, about override, do you mean the "Allow override" option is checked (in the Playback Settings tab)? If this is what you meant, do note that it really is enabled by default, but LR will not apply the actual Override settings (done in the Override Settings window) if Override is not turned on -- please check that the light for the Override button (bottom left part of the Play panel) is red (which means it's turned off). By default, Override is set to OFF, but if it was accidentally enabled you may simply click on Override once to turn it off.
I hope this helps! If you are still having problems, do send a Diagnostic Report so we can troubleshoot right away.