In Windows Vista or in Windows Server 2008, the common dialog box crashes if the initial target of the dialog box points to a SMB 1.0 share on a remote computer

Consider the following scenario. In Windows Vista or in Windows Server 2008 you have an application that uses a common dialog box. When the application is running, the common dialog box crashes if the initial target of the dialog box points to a Server Message Block (SMB) 1.0 share on a remote computer.

Note Computers that are running Windows Server 2008 or Windows Vista support SMB 1.0 and SMB 2.0. When Windows Server 2008 or Windows Vista communicates with a Windows-based operating system that is running Windows XP or Windows Server 2003, SMB 1.0 is enabled.

This problem occurs if there are multiple virtual circuits within the connection, such as file change notifications, from the local computer to the remote computer.

This problem occurs because the Common Dialog APIs try to enumerate the remote file system so that it can display the folder and file view to the user. When the SMB command block is unavailable, the APIs crash while they wait for a command block to be freed. If the command block is not freed, the application crashes.

Microsoft has produced the following hotfix to prevent file change notifications from blocking Common Dialog APIs. However, if another operation, which uses the same kind of SMB command as the common dialog box, consumes the reserved command block, the Common Dialog APIs remain blocked.

Hotfix information

A supported hotfix is 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 the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix on a computer that is running Windows Vista, you must have Windows Vista SP1 or Windows Vista SP2 installed.

No prerequisites are required for computers that are running Windows Server 2008.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

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 and Windows Server 2008 file information notes

The MANIFEST files (.manifest) and MUM files (.mum) installed for each environment are listed separately. MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated component. The security catalog files (attributes not listed) are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows Server 2008 and of Windows Vista

For all supported x64-based versions of Windows Server 2008 and of Windows Vista

For all supported IA-64-based versions of Windows Server 2008

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:
To work around this problem, follow these steps:

1. Click Start, type regedit in the Start Search box, and then press ENTER.
2. Locate, and then click the following registry subkey:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Lanmanserver\Parameters
3. Right-click the MaxCmds registry entry, and then click Modify.
4. Increase to a value that is more fitting for your needs.
   
   Note The default value for the MaxCmds registry entry is 50.
5. Exit Registry Editor.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about new networking features in Windows Server 2008 and in Windows Vista, visit the following Web site: For more information about Common Dialog Box library, visit the following Web site:

Additional file information for Windows Server 2008 and for Windows Vista

Additional files for all supported x86-based versions of Windows Server 2008 and of Windows Vista

Additional files for all supported x64-based versions of Windows Server 2008 and of Windows Vista

Additional files for all supported IA-64-based versions of Windows Server 2008