I have a Javascript function that is called from the onchange method in a DropDownList. However I'm getting the error "Cannot have multiple items selected in a DropDownList." on line 14. This happens when the page is reloaded for other purposes. Why is it getting hung here when the method shouldn't even be getting called? Line 12: { Line 13: var hfSelected = document.getElementById("<%=hfSelectedValue.ClientID%>"); Line 14: var ddlExposure = document.getElementById("<%=ddlExposure.ClientID%>"); Line 15: hfSelected.value = ddlExposure.options[ddlExposure.selectedIndex].text + "|" + ddlExposure.options[ddlExposure.selectedIndex].value; Line 16: }