Assume that you run a service which queries the Win32_StartupCommand Windows Management Instrumentation (WMI) class on a computer that is running Windows Vista, Windows Server 2008, Windows 7, or Windows Server 2008 R2.

In this situation, all loaded user profiles occasionally cannot be unloaded successfully after the WMI query is finished. If the number of unloaded user profiles keeps increasing, the system resources may be exhausted. For example, the virtual address control block (VACB) may be exhausted.

Here is a sample scenario:

  • You run a service on a computer that is running Windows Server 2008.
  • The service queries the Win32_QuickFixEngineering WMI class first.
  • The service then queries the Win32_StartupCommand WMI class.

In this scenario, all loaded user profiles cannot be unloaded. If you open the HKEY_USERS registry subtree by using an administrator account, you find that the user profiles are still loaded.

Note: You can obtain more information about the loaded user profiles from the following registry subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList

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