Can only access certain files in a shared folder.

Some of the photos in my shared folder on my XP PC give my the error message
"photo gallery can't open this picture because you do not have permission to
access the file location" when I try to open them from my Vista laptop.
Other photos in the same folder are fine. If I go to the XP machine and cut
them out of that folder then paste them back in it works fine but this is
tedious. Anyone know of a fix?
Thanks.