that is exactly what is happening to me when i try to connect some of my computers together. try manually connecting them by typing this into ur IE address bar
You should also check on your laptop and make sure that you have sharing set up propery on it. You might have file and print sharing enabled on the desktop but not the laptop.
Also check that firewalls aren't getting in the way, i had a message like that ages ago that i couldn't figure out,in the end i realised ti was the firewall on my xp laptop