Have a look at:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000A0120000&ECategory=LabVIEW.LabVIEW+General
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000DD170000&ECategory=LabVIEW.LabVIEW+General
Hope that helps,
Michael