Can't write file over network

My desktop Vista reads and writes files to my laptop over my private network.
The laptop reads but does not write back. Windows firewall is disabled,
McAffee is set to allow file writes from the network. The folder is shared
and security is wide open. Both computers have the same netwrk name. Password
protection is OFF. The error message is "Access denied."

After right button click on the folder and opening Properties, Read Only
button is blue. I can click it to transparent and Apply, it enters the
"unset read only" dialog and then turns transparent. But closing and
reopening the folder shows it returned to blue.

Any ideas? Linux?