1. Your sound card could be going bad.
2. A component in your system could be going bad.
3. Vacum out the dust in your system.
4. Have you recently moved an active electrical component near your PC? Even next to the wall in the other room.
5. Try moving the PC to a location away from other electrical compontents and test your sound.
6. Turn off your PC and reseat all of your cards and ram.<---if the sound card is bad this may well finish it off..
7. Check your power cable and DMI cable to your LCD.
8. Remove your throttel and stick from the PC and test your sound.
9. Check your fans for vibrations.
10. Get a younger gerbil and a new teflon bering wheel for it to run in.......
11. Is your cordless phone system sitting right next ot your PC?
12. Humm Ride of the Valkyrie louder and ignor the sound........
13. Borrow a sound card from a freind to see if your current card is going bad.