network problem

Hi, hope someone can help. I am trying to network my desktop and laptop both running windows xp. My desktop is connected (via ethernet cable) to a linksys wireless router which my laptop also uses to connect wirelessly to the internet (no problem so far). I have run the network setup wizard on both computers, and enabled file and printer sharing. I can access the files on my laptop from the desktop no problem, the problem is when i try to access files and/or use the printer on my desktop from my laptop. My laptop shows my desktop as a "workgroup computer" however when I try to click on it, and access files I receive the following message "logon failure: the user has not been granted the requested logon type at this computer"... it tells me that the desktop "is not accessable. you might not have permission to use this network resource. contact the network administrator of this server to find out if you have access permissions." I don't understand what else needs to be done, as I did not have to do anything special to allow the desktop to access the laptop.