You cannot set the maximum number of nested windows in Windows Vista or in Windows Server 2003

In Microsoft Windows Server 2003 or in Windows Vista, you cannot set the maximum number of nested windows.

A program can create up to 50 nested windows. If an application tries to create more than 50 nested windows in a window hierarchy, the nested windows that are created after the first 50 may not work.

This problem occurs because the maximum number of nested windows is hard-coded in the Win32k.sys file.

Windows Vista service pack information

To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Windows Vista 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 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 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.After you apply this hotfix, you can set the maximum number of nested windows by using a registry entry. For more information, see the instructions in the "Registry information" section.

Prerequisites

No prerequisites are required.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

Registry information

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To set the maximum number of nested windows, 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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type USERNestedWindowLimit, and then press ENTER.
5. Right-click USERNestedWindowLimit, and then click Modify.
6. Under Base, click Decimal.
7. In the Value data box, type a new value.
8. Click OK, and then exit Registry Editor.

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, 32-bit versionsWindows Vista, 64-bit versions

Windows Server 2003 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 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 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.After you apply this hotfix, you can set the maximum number of nested windows by using a registry entry. For more information, see the instructions in the "Registry information" section.

Prerequisites

To apply this hotfix, you must have Windows Server 2003 Service Pack 1 or Windows Server 2003 Service Pack 2 installed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

Registry information

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To set the maximum number of nested windows, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type USERNestedWindowLimit, and then press ENTER.
5. Right-click USERNestedWindowLimit, and then click Modify.
6. Under Base, click Decimal.
7. In the Value data box, type a new value.
8. Click OK, and then exit Registry Editor.

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 Server 2003 with Service Pack 2, x86-based versionsWindows Server 2003 with Service Pack 2, x64-based versionsWindows Server 2003 with Service Pack 2, Itanium-based versionsWindows Server 2003 with Service Pack 1, x86-based versionsWindows Server 2003, x64-based versionsWindows Server 2003 with Service Pack 1, Itanium-based versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Vista Service Pack 1.

The same problem occurs in Microsoft Windows XP. To obtain a hotfix for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base:For more information about the terms that are used to describe software updates, click the following article number to view the article in the Microsoft Knowledge Base: