A Service May Not Set Hooks on 32-bit GUI Applications

ID: Q163892

The information in this article applies to:

Microsoft Windows NT Workstation version 4.0
Microsoft Windows NT Server version 4.0

SYMPTOMS

On a computer running Microsoft Windows NT 4.0, a Win32 Service cannot set a hook on a 32-bit GUI application.

CAUSE

When an interactive service wants to hook a user's process, it is not allowed to because the desktop opened does not have the DF_ALLOWOTHERACCOUNTHOOK flag set.

RESOLUTION

A fix was developed such that if "Allow Service to Interact with Desktop" is set, the service is allow to set hooks on a user's process. This fix requires Microsoft Windows NT version 4.0 Service Pack 2 to be installed.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Keywords : kbprg kbbug4.00 kbfix4.00.sp3 nt32ap NTSrvWkst prodnt
Version : 4.0
Platform : winnt
Issue type : kbbug