Problem:
Cannot access other computer in same network (LAN.
On XP PRo SP2.

Solution:
1st Make sure all the FIREWALL allowed you to be viewed from the network
2nd try to use your IP instead of your Computer NAME.

IF THESE ARE NOT WORKING, then….


1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. Locate and then double-click the following registry subkey:
   
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Lsa
3. In the right pane, double-click restrictanonymous.
4. Make sure that the value in the Value data box is set to 0, and then click OK.
5. Close Registry Editor.
6. Restart the computer.

Tested at my home network!!!!