No more sound after second X server

[Tux]

Hello

My Kubuntu (8.04) has no more sound after I started a second X server.
How can I get it back?
I tried a full reboot: no effect.
If I boot on the live CD, the sound works fine, so this is not a
hardware problem..

To get a second X server, I logged as another user in a console
(CTRL+ALT+F1), than I run:
startx -- :1

How can I correct this?
Why does this happened? How can I prevent this?

Thanks for your help