I had no problems with amarok, until I plugged an USB sound card on the laptop and Amarok started to play on both sound cards alternatively. It started playing on the USB sound card, then when it crossfaded to the next track, started playing on the laptop's sound card. When I skipped to the next song, the same happened... returned to play on the USB sound card (didn't check if this happen with the crossfader off).
So, I removed the USB sound card. After this, Amarok crashes when the crossfade is on and try to skip to the next song (like it was looking for the other sound card). Works fine when the crossfade option is off.
Hope it's clear enough.
How can I get Amarok to work like before I put the USB sound card?

Amarok 1.4.5
KDE 3.5.6
Kubuntu 7.04
Xine engine.