Check the following :-
NETBIOS over TCP/IP must be enabled for normal network browsing.
Turn off any firewalls for debugging
Some firewalls must be completely uninstalled to stop them from affecting your networking.
Check DHCP Client, DNS Client, TCP/IP Netbios helper, Computer Browser services they should be ON , on all the machines in the network.
If you encounter difficulties accessing computers that are visible in Network Neighborhood, make sure the computer being accessed has an account with the same name/password as the system connecting to it uses to login.
Check for the NIC drivers and their version