* * For Those Who Can't Connect, Part Deux * *

[verdyp]

Warning sent to XP SP2 users:
Microsoft still delivers SP2 as a beta for developers, and there are various issues that are solved differently in each of the different locales. There are small adjustments to the builtin firewall that varies depending on the time when you installed SP2.
For now SP2 specific components will not be automatically updated with Windows Update (which will be delivered automatically and supported officially by Microsoft only in several months).
During that time, we won't recommand to users to upgrade to SP2, unless they know how to configure the rules of its builtin firewall.
Note that this firewall service in SP2 highly depends on the availability of the UPnP components and the DCOM/RPC DCE port mapper. It may not work as expected or may not be configured correctly if either is disabled (there are several still unresolved security issues in DCOM/RPC DCE and in the UPnP and in the Microsoft XML Parser components that may make this firewall fail in its configuration.)
If the firewall can't be configured or its configuration cannot be read by the firewall, the firewall may run in its default mode, disabling the support of incoming ports you have configured.

I had such troubles in SP2 despite I had configured the necessary ports in its interface. If you still get into troubles, first disable the SP2 builtin firewall, and run the network connection wizard to reconfigure it and restart it (the Windows network wizard should restart the necesarry services). Then remap the needed ports. It worked for me.
Don't forget to open the Windows Event Log Viewer in the Administration Tools, to see if some services fail to start appropriately.

Also, there are issues if you have used in the past the ZoneAlarm firewall. When installing SP2, ZoneAlarm may have some of its components incorrectly registered, blocking your Internet connections after some random time.

Another issue is that the ZoneAlarm uninstaller did not remove all of its components in the past, and upgrading to SP2 reactivated some of them, making your Internet connection work unreliably. You can solve this problem by reinstalling ZoneAlarm (the current version, even the trial version), and uninstalling it if you don't need it anymore, as its uninstaller has been corrected.

More generally, avoid using both ZoneAlarm and the SP2 firewall at the same time. Choose one of them only: either disable the SP2 firewall and reconfigure ZoneAlarm or uninstall cleanly ZoneAlarm and configure the SP2 firewall. There does seem to exist some problems when both services are activated locally on the same system. You can experiment such problems even out of LimeWire, when just browsing the web or checking your emails; in Internet Explorer, a web page may be extremely long to appear, or you will see a static page showing the ZoneLabs logo and some tricky comments about how to "solve" the problem.

If this happens to you (notably if you have tried in the past a trial version of ZoneAlarm and then you thought you had uninstalled it), you'll need to reboot XP and reconnect ot the Internet at least to download the latest version of ZoneAlarm just to reinstall it before uninstalling it cleanly.