If the following conditions are true, you may experience intermittent communication failure between computers that are running Microsoft Windows Server 2003 or that are running Microsoft Windows XP:
The network adapter is configured to use checksum offloading.
Windows Firewall is turned on.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
To work around this problem, turn off checksum offloading on the network adapter. To do this, follow these steps:
Click Start, click Run, type regedit, and then click OK.
Locate and then click the following registry subkey: