What's their save location like? Make sure that your XP machine can see hidden files, and system hidden files, and then see if you can manually locate them on the XP machine.
Thank you for your answer. My XP's can see all types of hidden files. And the Win 7 machine lists all of them when you list them in Win 7 machine. But they can not be seen from the XP machines (I have tried with 3 different XP-machines in my same network). The funny thing is that those files that can not be seen are mixture of various filetypes: txt, pdf, xls. I have not been able to figure out the logic behind which type of files can been seen and which not. But they are always the exactly same files that can not be seen. Thank you for your efforts!