When you upgrade from Window 2000 Server with SP4 to Windows Server 2003 integrated with SP1, the System event log records:

Event Source: NetBT
Event Category: None
Event ID: 4311
Time: HH:MM:SS
Type: Error
User: N/A Computer: <Computer Name>
Description: Initialization failed because the driver device could not be created.

Windows redetects the network adapter during the upgrade, and erroneously posts an error condition. The adapter functions normally.

You may safely ignore this error.