My guess is you've got the output set to 24/32 bit, and you're playing a low sample rate MP3? (eg. 11025hz)
That will cause my SBAudigy to go "racing" (with any player), so I guess it may be the same with your SBLive... if that is the case, there's no point setting the output to anything over 16-bit with an SBLive anyway
