Thank you for your mail. It seems that Orbiter tried to download the 'UpdateBinary' application to this folder (Orbiter's folder):
01 08/26/05 9:28:55.796 Failed to save the UpdateBinary application to location 'C:/Programmi/Pluto/Orbiter/' <00353A78>
The only reason not to do it is to have a firewall/an antivirus enabled. What is the size of UpdateBinary from Orbiter's folder ?
Please try stop for a min that firewall/antivirus and restart Orbiter. It should try to update again and succeed.