What type of sound card? Sounds to me like the drivers for your card are corrupted. Try re-installing the audio drivers and if that fails, save your data and do a freah re-install of windows.
Happens when you're multitasking and you have onboard sound.
I sincerily doubt that its corrupted drivers.
An external soundcard - possibly more RAM would help if not solve it altogether.
Logic: choppy at initial install?
Choppy now..ran fine before?
Add additonal DXI type software recently?
Total on-baord Ram?
What components do you have? (PCI cards)
More info is always helpful. Don't spend any more money until you an answer these basic questions.
Check your hardware acceleration for your soundcard man. if it's at full? try cranking it down a knotch or 2. If it's at emulated? try moving it up. Hardware acceleration can be good or bad. It all really depends on how well it works with the software.