MRxSmb Event ID 50

I have 2 sites, SITE1 and SITE2 connected through an IPVPN 10mbtis link.

All the users on SITE1 cannot save word documents on the File/Print server located in SITE1 (check attachment 1)
All the users on SITE1 cannot save word documents on any shared sessions on the other XP clients in SITE1 (check attachment 1)

In addition to this error, on the Event viewer all the users are getting an MRxSmb Event ID 50 (check attachment 2)

I took the below steps but unfortunately the problem still there:

1) I followed the steps on the File/Print server, the Symantec article referred by the Microsoft knowledge base:
http://seer.entsupport.symantec.com/docs/260805.htm 

2) I uninstall Office 2003, install again.

3) Change from dynamic IP to static IP.

4) I changed the NetBIOS settings to be over TCP/IP.

5) I tried on word 2007 it works fine but word 2003 not.

6) I check the enablesecuritysignature value under the following key in the registry and it was set to 0.
    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Lanmanserver\Parameters

7) I check the write cache option on the File/Print server disks and it was disabled.

8) Have the latest updates for MS Office and MS Windows.

9) Change the Network speed on the NIC adapter from Auto to 100 Full and Half.

10) Restart all the network equipments at including the File/Print server.

11) There is no problem using it through CITRIX.

12) I tried saving from SITE1 to SITE2 XP machine, it worked fine.

This problem is happening on all the machines in SITE2.

Please help!