HELP my HDTV System has noise and sudden pause


Help, guys, I've been struggling with this for a long time, and still can't get it solved.

The music play back (and movie audio) will have random (not always) electrical noise in there, it's very short, normallly 0.1-0.2 second. Also, it will pause (no sound at all) for 0.1-0.2 second, and keep on playing. It only happends with my HDTV-PC, but doesn't come up with my DVD player.

I use to have this problem with my old system, though it was the anmp, then though it was the PC, maybe the sound card?

After replaced everything, I am still haveing this problem, now I really have no idea what's going on, can someone please help to think what's the reason? Thanks.

Current system:
PC: Shuttle PC SG33G5M, Intel Q4 6600 CUP, 4GB ram, 500GB SATA Hard Dirve,
Realtek High-Definition Sound Card,
Connection: Optical digital (Toslink) to receiver.
Receiver: Onkyo Sr805
Power: Belkin PF30 PureAV power Conditioner

Old System:
PC: Dell Inspion 510,4GB Ram, 250 GB hard drive,
Sound card: X-Fi Music sound card.
Connection: Co-Axale to receiver
Receiver: Onkyo Sr-505
jaguarcondor
Just to add a little bit more information.

I tested all possible senarios, and it seems like if I put Defaul audio output format as "2 Channels", and disable all the effects (e.g. DTS output, etc).all the problems are gone. If I put the DTS Live or DTS interactive back, the problem appears. Guess there is some special configurations need to be done.

However, if I use 2 Channels as default, I won't be able to do any 7.1 simulation, or expand any 2 channels to surround sound.

Anyone can offer any suggestions?

thanks.
Reading around found that Onkyo and Yamaha receivers can't play DTS MA correctly seems like.

Does anyone has similar problems?
As for the pausing, make sure your pc CPU usage is as close to 0% as possible when idle, you could have apps running in the backround that are not needed, and services too.