I think I know what's happening with RadAlert, RadConfirm,... buttons in my app.
You can find the origin at this forum thread: Command.CanExecute() on RadButton inside RadBusyIndicator causes unexpected (wrong) behavior on RadButton.IsEnabled property
So, sometime ago, one of telerik's modification caused, sometimes, unexpected behavior in button's IsEnabled property. Sometimes, buttons with Command property set were enabled although the CanExecute command method returns false.
As you can observe in the thread, I created a custom behavior that was applied by default to all RadButtons and RadRibbonButtons in the application.
I think this behavior is causing that RadConfirm, RadAlert,... buttons appears disable. Probably you have modified the behavior of the IsEnabled property for buttons and now my behavior is invalidated.
So, can you confirm that actually IsEnabled property behaves as expected and that I can safely remove my custom behavior?