What Xhi says is important. That's true.
But, if after checking the workgroup settings it still does not work: how did you set the manual IP addresses? If you set that directly from Windows I think it would be better to leave them automatic. Check the automatic IPv4 addresses, and the IPv4 Default Gateway (this is what I called Access Route, sorry for that):
Select Control Panel from the Start menu.
Select Network and Internet Connections and then Network Connections.
Click the Local Area Connection icon under LAN or High-Speed Connection.
Click View status of this connection in the Network Tasks frame.
When the Local Area Connection Status window appears, click the Support tab.
Go to the "Network and Sharing Center", and click on the "View status" link. On Windows 7 click the link with the name of the network in the same area of the window:
And click on "Details":