Sound problems with aim and sometimes msn

Okay, this is my little sister's new laptop, an hp Pavilion media center zd7000, it has xp media center edition on it. And lately the sounds that aim plays when receiving an im are extremely garbled. This happens everytime an im is received now, it started slowly only occassionally garbling the im received sound. Msn also sometimes sounds garbled when it tries to say "good morning" or whatever. The computer plays audio files without a problem, so I am not sure if these are program specific or hardware related.

Has anyone else had this sort of problem? Does anyone have any suggestions?

I have tried reinstalling aim, but the same thing happens....

Please help!!!!