Проблема с функцией SetThreadContext

<DllImport("kernel32.dll")> _
Private Shared Function GetThreadContext(ByVal hThread As IntPtr, ByRef lpContext As CONTEXT) As Boolean
End Function
 
<DllImport("kernel32.dll")> _
Private Shared Function SetThreadContext(ByVal hThread As IntPtr, ByRef lpContext As CONTEXT) As Boolean
End Function
 
Private Declare Function Thread32Next Lib "KERNEL32.dll" (ByVal hSnapshot As Integer, ByRef lpte As THREADENTRY32) As Integer
 
<DllImport("Kernel32", EntryPoint:="GetModuleHandleA", ExactSpelling:=True, CharSet:=CharSet.Ansi, SetLastError:=True)>
    Private Shared Function GetModuleHandle(ByVal lpModuleName As String) As Integer
    End Function
 
Private Declare Function CreateToolhelp32Snapshot Lib "kernel32" _
        (ByVal dwFlags As SnapshotFlags, ByVal th32ProcessID As UInteger) As IntPtr
    Private Declare Function Process32First Lib "kernel32" (ByVal hSnapshot As IntPtr, _
                                                ByRef lppe As PROCESSENTRY32) As Boolean
    Private Declare Function Process32Next Lib "kernel32" (ByVal hSnapshot As IntPtr, _
                                                ByRef lppe As PROCESSENTRY32) As Boolean
 
Public Declare Function OpenThread Lib "kernel32.dll" (ByVal dwDesiredAccess As ThreadAccess, ByVal bInheritHandle As Boolean, ByVal dwThreadId As UInteger) As IntPtr
 
Public Declare Function SuspendThread Lib "kernel32.dll" (ByVal hThread As IntPtr) As UInteger
    Public Declare Function ResumeThread Lib "kernel32.dll" (ByVal hThread As IntPtr) As UInteger
 
Public Declare Function CloseHandle Lib "KERNEL32" _
    (ByVal hObject As Int32) _
    As Boolean
 
Private Const STANDARD_RIGHTS_REQUIRED2 = &HF0000
Private Const SYNCHRONIZE = &H100000
Private Const THREAD_ALL_ACCESS = STANDARD_RIGHTS_REQUIRED2 Or SYNCHRONIZE Or &H3FF
 
<StructLayout(LayoutKind.Sequential)> _
    Public Structure CONTEXT
 
 
        Public ContextFlags As UInteger
        'set this to an appropriate value
        ' Retrieved by CONTEXT_DEBUG_REGISTERS
        Public Dr0 As UInteger
        Public Dr1 As UInteger
        Public Dr2 As UInteger
        Public Dr3 As UInteger
        Public Dr6 As UInteger
        Public Dr7 As UInteger
        ' Retrieved by CONTEXT_FLOATING_POINT
        Public FloatSave As FLOATING_SAVE_AREA
        ' Retrieved by CONTEXT_SEGMENTS
        Public SegGs As UInteger
        Public SegFs As UInteger
        Public SegEs As UInteger
        Public SegDs As UInteger
        ' Retrieved by CONTEXT_INTEGER
        Public Edi As UInteger
        Public Esi As UInteger
        Public Ebx As UInteger
        Public Edx As UInteger
        Public Ecx As UInteger
        Public Eax As UInteger
        ' Retrieved by CONTEXT_CONTROL
        Public Ebp As UInteger
        Public Eip As UInteger
        Public SegCs As UInteger
        Public EFlags As UInteger
        Public Esp As UInteger
        Public SegSs As UInteger
        Public Rip As UInteger
        ' Retrieved by CONTEXT_EXTENDED_REGISTERS
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=512)> _
        Public ExtendedRegisters As Byte()
 
    End Structure
 
Public Enum CONTEXT_FLAGS As UInteger
        CONTEXT_i386 = &H10000
        CONTEXT_i486 = &H10000
        CONTEXT_CONTROL = CONTEXT_i386 Or &H1
        CONTEXT_INTEGER = CONTEXT_i386 Or &H2
        CONTEXT_SEGMENTS = CONTEXT_i386 Or &H4
        CONTEXT_FLOATING_POINT = CONTEXT_i386 Or &H8
        CONTEXT_DEBUG_REGISTERS = CONTEXT_i386 Or &H10
        CONTEXT_EXTENDED_REGISTERS = CONTEXT_i386 Or &H20
        CONTEXT_FULL = CONTEXT_CONTROL Or CONTEXT_INTEGER Or CONTEXT_SEGMENTS
        CONTEXT_ALL = CONTEXT_CONTROL Or CONTEXT_INTEGER Or CONTEXT_SEGMENTS Or CONTEXT_FLOATING_POINT Or 
        CONTEXT_DEBUG_REGISTERS Or CONTEXT_EXTENDED_REGISTERS
    End Enum
 
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _
    Public Structure THREADENTRY32
        Friend dwSize As UInt32
        Friend cntUsage As UInt32
        Friend th32ThreadID As UInt32
        Friend th32OwnerProcessID As UInt32
        Friend tpBasePri As UInt32
        Friend tpDeltaPri As UInt32
        Friend dwFlags As UInt32
    End Structure
 
Public Structure PROCESSENTRY32
        Public dwSize As UInt32
        Public cntUsage As UInt32
        Public th32ProcessID As UInt32
        Public th32DefaultHeapID As IntPtr
        Public th32ModuleID As UInt32
        Public cntThreads As UInt32
        Public th32ParentProcessID As UInt32
        Public pcPriClassBase As UInt32
        Public dwFlags As Int32
        <VBFixedString(260), MarshalAs(UnmanagedType.ByValTStr, SizeConst:=260)> _
        Public szExeFile As String
    End Structure
 
        For Each p As Process In Process.GetProcessesByName("taskmgr")
            Const TH32CS_SNAPTHREAD = &H4
            Dim ctx As New CONTEXT()
            ctx.ContextFlags = CONTEXT_FLAGS.CONTEXT_ALL
            Dim k32 As IntPtr = GetModuleHandle("Kernel32")
            Dim te32 As New THREADENTRY32()
            Dim pe32 As New PROCESSENTRY32()
            te32.dwSize = Marshal.SizeOf(te32)
            pe32.dwSize = Marshal.SizeOf(pe32)
            Dim hSnap As IntPtr = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0)
            If Process32First(hSnap, pe32) Then
                While Thread32Next(hSnap, te32)
                    If p.Id = te32.th32OwnerProcessID Then
                        Dim hThread As IntPtr = OpenThread(THREAD_ALL_ACCESS, False, te32.th32ThreadID)
                        SuspendThread(hThread)
                        GetThreadContext(hThread, ctx)
                        ctx.Eip = CUInt(GetProcAddress(k32, "ExitProcess"))
                        SetThreadContext(hThread, ctx)
                        ResumeThread(hThread)
                        CloseHandle(hThread)
                        CloseHandle(hSnap)
                    End If
                End While
            End If
        Next