Networking Troubleshootings In XP SP2

A Few Most Common Problems:-

NET SEND messages no longer received:-
Workaround:-

First enable the File and Printer Sharing exception in the firewall.

Next,Go to Control Panel, Admin Tools, Services, double-click on the Messenger service, set its start type to Automatic.

FTP folder error:-

Workaround:-
Open Internet Explorer>Tools>Internet Options>Advanced Tab>Put a check mark next to: Use Passive FTP>Put a check mark next to: Enable Folder View of FTP sites

Dial-up connections or Remote Access Connection Manager problems:-

See:-You cannot create a network connection after you restore Windows XP

http://support.microsoft.com/?kbid=329441

Workgroup is not accessible:-

If you get one of these symptoms or error messages or a similar one:
You cannot access shares on other computers.
You cannot locate other computers in the workgroup.
When you double-click the workgroup in My Network Places, you get the error message: Workgroup is not accessible. You may not have permission to use this network resource.
Workgroup is not accessible. The list of servers for this workgroup is not currently available.

Workaround:-

1>make sure the File and Printer Sharing exception is enabled in the firewall.

2>Make sure the Computer Browser service is running. To have the Computer Browser start automatically, select Administrative tools, Services, and change the Start setting for Computer Browsing to Automatic. You can then reboot the computer or start the service manually by clicking on the Start button.

3>Uninstall third party client software that can interfere with the networking settings.

Winsock corruption:-It may be caused by adware or a virus. Service Pack 2 adds a new command to repair this Winsock corruption problem.
netsh winsock reset catalog

Firewall blocks LPR printing:-The LPR protocol uses TCP Port 515, which is, by default, blocked by the firewall.As a result When you try to print to an LPR printer, the print job fails without any further error message.
Workaround:-Add an exception for TCP port 515 in the firewall.,name it LPR. Enable it only for the local subnet, unless the printer is outside.

Related KB Articles:-
List of networking fixes in Windows XP Service Pack 2

How to troubleshoot wireless network connections in Windows XP Service Pack 2

You cannot modify Windows Firewall settings for an AOL dial-up network connection by using Network Connections in Control Panel in Windows XP Service Pack 2

How to remotely administer a printer through a network share when you use Windows XP Service Pack 2 in a workgroup environment

You cannot configure Windows Firewall settings or Security Center settings on a Windows XP Service Pack 2-based client computer that is in a Windows Small Business Server 2003-based network

You cannot check for updates to the broadband networking software after you install Windows XP Service Pack 2

Error message when you try to run the Wireless Network Setup Wizard after you update to Windows XP Service Pack 2

A physical hard disk drive on your computer may appear as a removable drive when you run the Wireless Network Setup Wizard in Windows XP Service Pack 2

The Computer Browser service does not start and event ID 7024 is logged when you restart your Windows XP Service Pack 2-based computer

You receive an "Access denied" or "The network path was not found" error message when you try to remotely manage a computer that is running Windows XP Service Pack 2

Using Internet Connection Sharing with user profiles You cannot scan images with a network scanner when Windows Firewall is turned on in Windows XP Service Pack 2

You can use Windows Firewall to help protect network bridge connections in Windows XP Service Pack 2

Regarding more information on XP SP2 Firewall check it here:-Understanding Windows Firewall in Windows XP Service Pack 2
Description of the Windows Firewall feature in Windows XP Service Pack 2
http://support.microsoft.com/kb/843090