audio problems

OK, so I have a flight setup somewhere (doesn't matter where), and at the same time I'm running an audio file or streaming audio on iTunes or Windows Media Player. When I go to look at the spotplane view of my aircraft, all of a sudden, the sound stops and I loose about 30-35 frames per second, usually down to about 1-2 fps. According to WMP or iTunes, the file is still playing. Also, all audio from flight sim and everything else on the computer will not play unless I restart the computer. This has happened about 5 times now. What is going on? I will be checking back, so if there are any questions regarding the problem, please ask. Thanks!System Information:Processor: Intel Pentium 4, 2.4 GHz, 533 MHzOS: Windows XP Home, SP1Video Card: ATI Radeon 9600XTSound Card: Turtle Beach Santa CruzRAM: 512 MBHard Drive: Western Digital 120 GBHomebuilt