cannot copy (filename) acess denied

I am trying to backup files from my laptop to my desktop over a wireless connection. i get this message everytime i try to copy a file to my desktop. any ideas both are using xp sp2

 

Is it a file you have created?

If you right-click the file and choose properties, then go to the security tab, user group Administrators should have Full Control on the file in question. It could be that the file was created by another user or program and you are not included in the Administrators group for some reason, but you give yourself Full Control for here anyway.