Originally Posted by
AllCrackedUp6 What OS are you running? The phone gives you an error for ANY alert sound you try, not just the downloaded ones, correct? Does the problem fix itself after you reboot (either a battery pull or a soft-reboot?)
I had the same issue after upgrading to OS .439. The problem for me was a flashlight app (OneTouch) I had installed. This app is recognized by my phone as a "media event", because it uses the camera's flash (I think). After I exit the app, the new OS doesn't recognize the media event as ended, and doesn't let me play any alert sounds because of this.
I figured this out by looking at the event log (alt + lglg), and it logged my attempt to test an alert in my sound profiles as something like "Cannot play sound while another media event is ongoing" (this is just the gist of the error, I can't remember the exact phrasing).
Only way I found around it was to reboot. Even if you don't have the flashlight app, it's possible the same issue is being caused by another app.