"attacks" means what exactly - when your antivirus pops up a hacker warning?. When you shoot at something in the game?.
Hmmm (thinking cap on) does your sister's machine have Nero installed (it is mainly a CD burning package, but does all sorts of other things including audio and video playback now I think? - anyway there are loads of Nero items in that file that do not seem to me to be about simply CD-burning!!). If not -
and you have the Nero installation CD to reinstall it 
! - maybe try uninstalling Nero and see what happens?
Myself - I would go the goldwave route, and convert to WAV as it is a Windows native format, even if it is larger in terms of disk space impact. MP3 on Windows seems to cause too much grief to bother,
if one is using it for mult-voice sound streams, as several third party replacement CODECS (or some integrated or low end sound cards) seem to only handle single MP3 streams. Which is OK for watching a movie or playing a song, but not for games.
We issued WW2 with WAV format sound instead of MP3 because of this (and added 50 or so MB of bloat to a ~100 MB installer).
The WinSPMBT sound system will also handle any other windows standard sound format, so .wma, .mid etc should work fine if you have problems with WAV. But we have only had one report of problems with WAV - that person (WW2 user) solved it with conversion to .wma.
Cheers
Andy