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    public static PropertyKey PKEY_Device_InstallState = new PropertyKey(0xa45c254e, 0xdf1c, 0x4efd, 0x80, 0x20, 0x67, 0xd1, 0x46, 0xa8, 0x50, 0xe0, 36);    // DEVPROP_TYPE_UINT32

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    public static PropertyKey PKEY_PNPX_InstallState = new PropertyKey(0x4FC5077E, 0xB686, 0x44BE, 0x93, 0xE3, 0x86, 0xCA, 0xFE, 0x36, 0x8C, 0xCD, 0x00000004); // VT_UI4 | VT_VECTOR

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public enum INSTALLSTATE

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    INSTALLSTATE_NOTUSED      = -7,  // component disabled

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    INSTALLSTATE_BADCONFIG    = -6,  // configuration data corrupt

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    INSTALLSTATE_INCOMPLETE   = -5,  // installation suspended or in progress

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    INSTALLSTATE_SOURCEABSENT = -4,  // run from source, source is unavailable

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    INSTALLSTATE_MOREDATA     = -3,  // return buffer overflow

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    INSTALLSTATE_INVALIDARG   = -2,  // invalid function argument

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    INSTALLSTATE_UNKNOWN      = -1,  // unrecognized product or feature

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    INSTALLSTATE_BROKEN       =  0,  // broken

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    INSTALLSTATE_ADVERTISED   =  1,  // advertised feature

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    INSTALLSTATE_REMOVED      =  1,  // component being removed (action state, not settable)

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    INSTALLSTATE_ABSENT       =  2,  // uninstalled (or action state absent but clients remain)

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    INSTALLSTATE_LOCAL    =  3,  // installed on local drive

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    INSTALLSTATE_SOURCE       =  4,  // run from source, CD or net

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    INSTALLSTATE_DEFAULT      =  5,  // use default, local or source

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Public Enum INSTALLSTATE

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Documentation

[INSTALLSTATE] on MSDN

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One could use the System.ServiceProcess.ServiceInstaller and System.ServiceProcess.ServiceProcessInstaller, but doing so will create an InstallState file that may be undesirable.

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static extern INSTALLSTATE MsiQueryProductState(string product);

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Declare Function MsiQueryProductState Lib "msi.dll" (ByVal product As String) As INSTALLSTATE

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Makes use of the INSTALLSTATE enum, which can be found here - http://pinvoke.net/default.aspx/Enums.INSTALLSTATE

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    private static extern INSTALLSTATE MsiQueryProductState(string product);

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        INSTALLSTATE state = MsiQueryProductState("{11111111-2222-3333-4444-555555555555}");