Sound distiortion issues

This issue has been driving me crazy, sound starts to distort when the PC has been in use for some time. This will make music and videos distort. It doesn't matter what player I use music and video will skip. If I start a youtube video the video will have distorted sound as it downloads and will only stop after the whole video is downloaded. When I listen to music and I go to a new web page the music will crack and pop. It fixes itself when I reboot but always comes back at random times.

I have updated all drivers and I'm still having the same issues.

My PC is a custom build from me:
Windows Vista Ultimate
MSI Neo2 (P35) Motherboard using onboard sound and onboard LAN
E2160 OC @ 3.0ghz (runs cool not a heat issue)
2GB A-Data DDR2 667 RAM (Passes Memtest not a RAM issue)
x800 GTO 256 Video Card (This old thing has been getting warm with light gaming.)
SATA HDD & SATA DVD (I'm not using any IDE)

Is this a hardware problem, integrated soundcard or LAN?

Try a new sound card driver, if that doesn't help buy a sound card - not Creative labs because theirs tend to hog the bus and that could be part of why you get the crackling already.

As for the other videos, distorted sound can have more than one cause, try updating your video and audio codecs. Try to isolate which video files corrupt by playing local copies instead of through your browser and find a commonality of audio & video codec that doesn't work right.

It shouldn't be a Lan issue, if the data doesn't come down the pipes fast enough the audio should drop, stop, not get garbled or crack and pop.

I installed a new sound card ENCORE ENM232-6VIA but it is still acting up. The sound is more of a skip/distortion and happens when the CPU is +70%.

I uninstalled and then reinstalled all codecs also like suggested above. I can't figure this out, help this is driving me nuts.