An Operating System With Multiple Log In

As I said, I'm new to XP, so I'm new to having an OS with multiple logins (I never set up user accounts with Win98). I set my new Dell up with two user accounts (mine and my wife's), and for some strange reason, I cannot get any sounds to play with windows "system events", such as signing on, signing off, error messages, minimizing/maximizing windows, etc. I have always assigned specific .wav files to specific system events without any problem on my Win98 PC, so I did the same thing with this one. I can assign sounds to event without any problem, and when I click the "play" button in the dialog box when setting up these sounds, everything sounds great. I've saved the scheme under my name, and told the system to apply it, but I get nothing (by the way, I think these worked the first time I turned on the PC out of the box, but they soon quit - long before I tried assigning specific .wav files to them). But when I change users to my wife's account, al! l the default settings work just fine (I have not attempted to change her sounds).