Bad crackling noises during music playback

When I start up my computer I experience sound crackinling, when I play music it always happens, sometiems with movies but generally it never happens during movies. I believe it may be somethign to do with system sound file being corrupt. maybe. but i have installed a SB live! 24 bit card and tried it in another computer, tried my speakers in another computer and both worked fine. i have updated the drivers. i have tried a different pci slot. i am pretty sure i disabled the onboard sound through unplugging it from the motherboard. but i may have left something out in that process, so let me know abotu that one. otherwise i don't know what to try next. suggestions so that i can actually listen to music wihtout craclking and skipping type noises, seeing as the new sound card only made the skiping/crackling noises sound nicer. thanks!

Post your system specs and are you overclocking anything?