Sound probs - any thoughts?

Well, a couple of nights ago I installed a bunch of add on mesh scenery as well as some land class files. Since then, I've been having major issues with the sound in the program. In a word, the sound seems to have become unstable. I am now routinely losing ATC (esp. when I change views) and the plane sounds remind me a bit of a record with a scratch and jump embedded on the plastic. These problems appear only in MSFS2002 - not in real player etc. I've uninstalled and re-installed the most recent turtle beach santa cruz drivers several times, but no permanent fix. Has anybody experienced this? Am I doomed to do a complete reinstall of MSFS2002 (what a pain) to fix it?Thanks. System info below. Dell p4 1.9 423 pinWin XP HomeTurtle Beach Santa Cruz Sound Card - driver: 5.12.1.4161GeForce 2 TNT Pro 64mg video card - driver: 2.1.8.3728 mgs ramSaitek and PFC controlsRecently installed: Need for Speed - Porche product. Thanks for any help. Colin