Spyware?
 

I have a new G4 and downloaded limewire and then some songs. Yesterday my sister in law opened some photos that I sent that had shown up as attachments (she has a pc). they had become slide shows with ads for different things including porn sites. when she sends them back they don't do the same on the mac. Help. I can only presume this is from limewire as I have no other software except a few old demo games downloaded. I know everyone seems to be saying that spyware is a pc problem but it seems I have sent that to her.
any ideas?