OK, just to check. Simple file sharing is UnChecked on both machines?
The file attributes are not set to read only or archive?
You have granted permissions to the files as everyone it has not worked? So the user names that you have given file access to, what group do they beloing to? i.e. Administrators? or Limited? or Guests? Or Power Users?
This later part is set under Administrative Tools -> Computer Management -> Users and Groups - > MemberOf Tab
Hope this helps..?