Since you have changed the IP on the first computer the second will not recognize it because it is looking for the old IP adress. What you may want to try is setting up an entirely new network connection with both computers. Delete the old network and start from scratch. Since WIndows only looks for a few select things to recognize if everything is working properly, if you change anything you may run into the problems like you are having - especially when it comes to networks. The easiest thing to try is delete the network connection from both computers and set up a new one.
Hope this helps!!
