This was reported earlier with another bug, but got missed. Sometimes resources don't allow you to select the headword in the navigation box, and get stuck on the page number. You can fix it by typing in a headword in the box. I think these are the relevant errors from the log:
2010-03-11 22:35:17.6796 1 Error WpfDataBinding System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
2010-03-11 22:35:17.6796 1 Error WpfDataBinding System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
2010-03-11 22:35:17.6796 1 Error WpfDataBinding System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
2010-03-11 22:35:17.6796 1 Error WpfDataBinding System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
2010-03-11 22:35:17.6796 1 Warn WpfDataBinding System.Windows.Data Warning: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='LDLS4.Panels.ResourcePanel.LocatorPane', AncestorLevel='1''. BindingExpression:Path=Entries[0]; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'NoTarget' (type 'Object')
2010-03-11 22:35:17.6796 1 Warn WpfDataBinding System.Windows.Data Warning: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='LDLS4.Panels.ResourcePanel.LocatorPane', AncestorLevel='1''. BindingExpression:Path=Entries[0]; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'NoTarget' (type 'Object')
