Network File Sharing

I have a simple two computer home network. Office PC wired into a linksys
wireless router and connected to broadbanc internet. A laptop downstairs
with wireless network connection.

I have enabled file sharing and shared, amongst other things, "My
Documents". I have also checked the "allow network users to change my files"
box. I can see, use, rename and delete stuff OK, but I cannot rotate a
picture. Is this a "feature", or have I missed something??