To reproduce: Add a RadDropDownList and use the following code snippet:

            this.radDropDownList1.DropDownStyle = RadDropDownStyle.DropDownList;
            this.radDropDownList1.Items.Add("ABC");
            this.radDropDownList1.Items.Add("BCA");
            this.radDropDownList1.Items.Add("ADE");
            this.radDropDownList1.Items.Add("DEF");
            this.radDropDownList1.Items.Add("DHJ");

Initially, no item is selected. If you press "A", the first item "ABC" is supposed to be selected. However, RadDropDownList selects item "ADE".