It can take a couple of reboots to get it all working, but if that doesn't fix it, since your PCs can see each other, there is probably some firewall software still running, e.g. symantec/norton.
If you know the IP address of the desktop, you can try and mount a desktop volume on the laptop. Set a volume to be shareable on the desktop using properties on the C: drive icon in my computer, then
My Computer->tools->map network drive
You can use, for example, \\192.168.1.2\C$ (assuming that is the share name).
That may force it to all work, once you've mapped drives in both directions.
It can be a sod to make this stuff work, usually there's some software in the way.
BW
Also, try running the share wizard on both machines.