All .au files are spammed junk. Likewise a reasonable % of WMA files are spam. Many of them dangerous (contain viruses & worse.)

Sounds like you are using LW 4?

Add .au and .wma to your keyword filters so they will not show up in search results. Make sure you put the dot in front of those extensions else you may filter out a filename that is good.

If using LW 5 you will find keyword filter under Tools -> Options -> Search. Alternatively you could add to extension filter instead.