What could LAN to Fail

[Mir96TA]

Two Computers
1 LAN
1 WLAN
1 Router
OS :XP Pro SP3 (installed few days ago)
Fiewall : XP (disable)
AntiVirus: NONE
Two Shared Folder In their Local HDD with Local Network User to Modify Option On
Acess To Internet: YES
Protocal: TCP/Ip Client for MS, File and Printer Sharing for MS. QOS Packet Scheduler
Computer can ping them Self but not each other.
What could be Wrong here ? Why I can't see other computer ?
Or I should ask where should I start for Trouble shooting

 

[JackMDS]

Look at the Firewall entries and exceptions and makes sure that every thing is checked (even if you do not want to use the Firewall).

Since SP3 adds security look at the all Sharing and permissions to make sure that nothing is blocked.

If you used the Guest Account make sure that it is On.

 

[Mir96TA]

I have enable the Wired AutoConfig on both computers
Still no luck
I am not sure what to look for in SP3 for Security

 

[Mir96TA]

I have also installed the MS KB951830
No Luck