xrun problem

Hi. I’m trying to record my voice for a song using Ardour 2.8 on Ubuntu 8.10. I’m using a Labtec mic ( http://ecx.images-amazon.com/images/I/3133C9K7ZJL.SL500_AA280.jpg ). I imported to Ardour the music in WAV format and I record my voice while I listen to the music at the same time with Ardour as I do always but this time while I’m recording my voice I can hear some skipping sounds in the music and some marks call it “xruns” appears from nowhere making my voice and the song a skipping sound.

How do I prevent this?

(Sorry for my bad english I usually speak Spanish)

Install realtime kernel-rt