Unable to copy files to external storage

[namurell]

I purchased a new desktop computer with vista ultimate on it a few months ago. And for as long as I know when ever i create a file on this computer I am unable to transfer the said file to an external HD or flash drive. I recieve no error messages of any kind. It always looks like it will work. Then when I unplug the external medium and take it to another computer, like my laptop, with the same OS, the files simply no longer exist. Its like I never put them on the HD. So I go back to the orriginal computer and plug back in the HD and low and behold the files ARE there. I am just unable to view/ read them or anything for that matter on another computer with the same OS or not. I figure it has to be some sort of weird new permission in vista somewhere that i cannot locate. I could use whatever help you guys can give me. I am desperate at this point. The computer is useless until I get this fixed.