I want to be able to move a file across my home network (both PCs are Vista).
I have shared the destination folder with "Everyone" to be a co-owner. I do
not have passwords set up.

I can "see" the destination folder across the network and can open documents
in it, but it will not allow me to move files into it. The weird thing is, I
encountered this for the first time a couple of days ago. The folder was
shared, but I could not move a file into it. That was when I looked into
sharing and realized that I had to change permission lever to "co-owner" in
order to create documents. Once I updated the sharing, I was allowed to move
the file. However, today I am not allowed to perform the very same action; I
get "Destination Folder Access Denied, you need permission to perform this
action".