Microsoft KB Archive/940480

= A 32-bit application cannot use the NetBIOS API to receive data on a computer that is running a 64-bit version of Windows Vista =

Article ID: 940480

Article Last Modified on 9/11/2007

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APPLIES TO


 * Windows Vista Enterprise 64-bit Edition
 * Windows Vista Home Premium 64-bit Edition
 * Windows Vista Ultimate 64-bit Edition
 * Windows Vista Business 64-bit Edition

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SYMPTOMS
You are running a 32-bit application on a computer that is running a 64-bit version of Windows Vista. The application uses the NetBIOS API to communicate over the network. In this Windows on Windows 64 (WOW64) environment, the 32-bit application can open a connection, and it can send data. However, the application cannot use the NetBIOS API to receive data.

For example, the 32-bit application successfully makes an NCBSEND command call. However, the NCBRECVANY command cannot receive data correctly.

Note This problem does not occur in the following scenarios:
 * You run the 32-bit application in a 32-bit version of Windows Vista.
 * You compile code for the 32-bit application into a 64-bit application. Then, you run the 64-bit application in the 64-bit version of Windows Vista.



CAUSE
This problem occurs because of an error in the NetBIOS interface driver (NetBIOS.sys). When the NetBIOS interface driver is receiving data, the driver sometimes does not convert the network connection block (NCB) structure from the 64-bit version to the 32-bit version. Therefore, the 32-bit application cannot understand the NCB structure.



Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
No prerequisites are required.

Restart requirement
You have to restart the computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other previously released hotfixes.

Registry information
To use one of the hotfixes in this package, you do not have to make any changes to the registry.

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Vista, 64-bit versions


STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
Windows on Windows 64 (WOW64) is a compatibility environment that enables 32-bit Windows-based applications to run on 64-bit Windows-based operating systems.

For more information about the same problem in Windows Server 2003, click the following article number to view the article in the Microsoft Knowledge Base:

940074 A 32-bit application cannot use the NetBIOS API to receive data on a computer that is running a 64-bit version of Windows Server 2003

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional query words: NetBIOS 32-bit 64-bit receive WoW64 NCBRECV NCBSEND VISTA x64

Keywords: kbfix kbqfe kbpubtypekc kbexpertiseadvanced kbhotfixserver KB940480

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