audio problems

Hello.
When installed Ubuntu Hardy Heron I had problems with audiom meaning not that I don't hear anything but that I got audio, the problem is that the sounds are disturbed, as if there is a granular disturb in the background.

Well, telling this in the simplest way, in audio file and video audio is disturbed and NOT CLEAR.

Well the first time I played an mp3 the system told me that there were no codecs and it installed them automatically. The result was this, I finally got audio but it was not good.
That's what happened back then.

Thanks in advance for your help.
Dorian

ProblemType: Bug
Architecture: i386
Date: Fri May 30 11:49:47 2008
DistroRelease: Ubuntu 8.04
ExecutablePath: /usr/bin/yelp
NonfreeKernelModules: nvidia
Package: yelp 2.22.1-0ubuntu2.8.04.1
PackageArchitecture: i386
ProcEnviron:
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: yelp
Uname: Linux 2.6.24-17-generic i686