Some directories get ignored when you perform a search in Windows (not only Vista) maybe you can enable the search to scan also that special folders, but I never had to, so I don't know how to enable it.
Anyway, try to use
this little tool I made, it should find your preferences file and make a backup copy of it (remember to close BSplayer before you launch it)
Under Vista BSplayer.xml should be located in
C:\Users\<users>\AppData\Roaming\BSplayer (I'm not sure)
I don't remember if it also works under Vista, but you can give it a try
