Programs that require many NT User handles may stop working when they reach approximately 10,000 handles. For example, this might occur when a program tries to use many NetDDE links.
There is a hard-coded limit of 10,000 NT User handles. This is designed to prevent "bad" (incorrectly behaving) programs from allocating too many NT User handles.
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.
The English version of this fix has the file attributes (or later) 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 tool in Control Panel.
Date Time Version Size File name
13-Aug-2002 12:04 5.1.2600.54 1,671,040 Win32k.sys
Required Registry ValuesWARNING
: If you use Registry Editor incorrectly, you may cause serious problems that may
require you to reinstall your operating system. Microsoft cannot guarantee that you can solve
problems that result from using Registry Editor incorrectly. Use Registry Editor at your own
To use this hotfix, you must create or modify the following registry values to specify the number of NT User handles that you want to allow. The maximum number is 18,000.
HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows\USERPostMessageLimit (REG_DWORD)
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.