On my dad's account, videos opened in WMP have no sound
---they have sound in all other video playing programs (we tried quicktime and BS player)
--- they have sound in WMP on MY account

BTW, while "use one of those other programs" may seem like an easy answer, he's old and stubborn. He told me that "there's no reason it shouldn't be working" and that something I did messed it up; so I'm in charge of fixing it. I've tried other net resources to no avail, so I was hoping I could find some help here.