Internet Explorer does not play audio after Quicktime or Media Player Classic is installed.

Try this fix:

1. From within Internet Explorer, choose Tools > Manage Add-Ons
2. From the "Show:" drop-down box, choose
     "Add-ons that have been used by Internet Explorer"
3. Scroll down to any items beginning with "Quicktime";
      click on each item and choose Disable (in the Settings area at the bottom)
4. After you've disabled each Quicktime item, click "OK" in the bottom right corner.
5. Exit out of Internet Explorer
6. Restart Internet Explorer

Hopefully the above will fix the problem.