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A request may return a null pointer to the IFontDisp interface when a program that uses the Windows XP SP2 version of the Atl.dll file requests access to the ambient font property
Article ID: 887569 - View products that this article applies to.
You may experience the following problem when a program uses the Microsoft Windows XP Service Pack 2 (SP2) version of the Atl.dll file to host ActiveX controls. When a program that uses this version of the Atl.dll file requests access to the ambient font property that is in an Active Template Library (ATL) host container, the request may return a null pointer to the IFontDisp interface.
When the null pointer is returned, an access violation may occur because most ActiveX controls do not recognize a null pointer. The program may stop responding. Or, the ActiveX controls may not work correctly.
This problem occurs because of a regression in the version of the Atl.dll file that is included with Windows XP SP2.
The control makes a call to the IAxWinAmbientDispatch::get_Font method. This call then causes the ATL!ATL::CAxHostWindow::get_Font method to be called. The call to the ATL!ATL::CAxHostWindow::get_Font method returns an S_OK HRESULT result. However, a null pointer is returned to the IFontDisp interface. Programs typically assume that a valid pointer is returned if the interface returns an S_OK HRESULT result. However, the control does not recognize the null pointer that is returned to the IFontDisp interface. Therefore, you experience the problems that are described in the "Symptoms" section.
Hotfix informationA 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:
http://support.microsoft.com/contactus/?ws=supportNote 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 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 tool in Control Panel.
Date Time Version Size File name --------------------------------------------------------- 11-Jan-2005 23:25 3.5.2284.1 58,880 Atl.dll
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/824684/ )Description of the standard terminology that is used to describe Microsoft software updates