Vista - Unable to move file

I sometimes have two computers running (desktop and laptop) when I'm working
on complex spreadsheets. I usually open the file on the desktop and
immediately re-save it with a new name, then open the original on the laptop
so I don't have two files open with the same name.

Sometimes when I open the file on the laptop I get a message that says
Foldershare is unable to move the file and if I have it open I should close
it. When I close the file, foldereshare then saves it with a different file
name that includes the name of the laptop on my network, which means I then
can't reopen it from the recent files list.

Why is Foldershare trying to move my file, where is it trying to move it to,
and why does it rename the file?