Discover DJ, sound is getting weard.

Hey everyone, when I'm using the Discover DJ with my external Fast Track sound card connected trough Asio4ALL, sometimes the speaker sound output gets some kind of "crunch" in it.
If I click on 48000 Hz (if it is on 41000 Hz) the sound gets normal, but in 10 minutes it's back.
What's the solution of this?
If I click on 48000 Hz (if it is on 41000 Hz) the sound gets normal, but in 10 minutes it's back.
What's the solution of this?