Excel file saving problem in the network

I have a problem in saving an excel file on to another pc in the network, which has windows xp. But before I used in both pc’s windows xp & that time there were no problem saving on to the other pc. Now I use windows 7 32bit (Service pack1) in my pc & other pc on network is windows xp. Im doing some thing on Microsoft Excel 2007 (password protected file) in windows7 pc & when I saving to windows...