Limited connectivity is generally due to lack of internet connection specially on Win7 PC.
Also because of improper IP assignment , bad connection ,etc.
Create an Ad-Hoc connection , Join Homegroup and select type as "Home network", and turn-on file sharing.
Now go-to Network places, and wait for the other computer to appear on the list.
Once its there , Code-in the login credentials for the computer you want to access.
It should be pretty easy using Ad-Hoc connectivity.