I thinik you could be suffering for an incorrectly attached CPU heatsink - modern processor will cut their speed dramtically if they are overheating which will translate into a complete inability to play audio from an audio application without distortion, dropouts, glitches etc.
The tell tale sign for me is that the CPU meter is going nuts as well, so I allmost guarantee this is the problem. I am assuming that the CPU cooler is adequately specified.
I am also guessing this could a first or second time you have built you own PC - can you remember what kind of heat transfer pad or paste was between the CPU and its cooler and if a pad - you *did* take the paper backing sheet of it?
If paste, did you stuck the right amount on? Too little and you dont get good contact between the CPU and the cooler, too much and it start to act as an insulator between the CPU and its cooler.
Another posible cause, but TBH this tend to only kick in when you are stressing you computer is that you have the an inappropriate CPU fan control mode mode set in the BIOS - I allways set it for max cooling and disable any BIOS options for speed step and anything else that degrade performance, however I *NEVER* switch off the thermal throttling options as they arfe what protects your CPU should you have a problem with the cooler - if you switch those off - you will fry your CPU in the event of a cooler failure of any kind.
Hate to say this, but this is a very good reason to buy pre-built systems from the likes of DV (yeh - no good to you now - I know
) etc unless you really know not only how to put a michine together for reliable operation, but also how certain kind of symtoms can related to hardware build problems.
Anyway - check your cooler - I'm absolutely sure thats the problem. If you have any doubt about correct mounting and application of heat transfer paste/pad etc, then read and follow the the mounting intructions carefully.
BTW - if the cooler had a heat trasnfer pad on it (intel standard coolers used to), and you toiok the paper off it, then it will stick to the CPU a little. Aso check that the cooler is very securely clamped down. If the CPU has allready overheated and been throttled, then the heat transffer pad may be near useless - if so, then the only option is to carefully scrap it off (Dont not use anything metal for this as it will badly score the soft metal of the cooler) and use a high quality thermal transfer paste - arctic silver for eg or some of the even better newer heat transfer pastes.
If you have doubts - then find a PC tech to do this for you.