Stop the screen saver and hibernation temporarily in VB.Net - vb.net

Question

I have a very long running syncronization task that cannot be interrupted by the screen saver or aggressive power saving modes. I want to make a single api call to stop power save mode and then restore it once the task is done.
The following code is peaced together from various other posts but it has no effect on XP's power management settings. What am I doing wrong? TIA!
Private Declare Function SetThreadExecutionState Lib "kernel32" (ByVal esFlags As Long) As Long
Public Enum EXECUTION_STATE As Integer
ES_CONTINUOUS = &H80000000
ES_DISPLAY_REQUIRED = &H2
ES_SYSTEM_REQUIRED = &H1
ES_AWAYMODE_REQUIRED = &H40
End Enum
Public Shared Sub PowerSaveOff()
SetThreadExecutionState(EXECUTION_STATE.ES_DISPLAY_REQUIRED Or EXECUTION_STATE.ES_CONTINUOUS)
End Sub
Public Shared Sub PowerSaveOn()
SetThreadExecutionState(EXECUTION_STATE.ES_CONTINUOUS)
End Sub
Here are the systems screensaver and powermode settings:
alt text http://img87.imageshack.us/img87/1600/25251376.jpg
alt text http://img403.imageshack.us/img403/8145/73347627.jpg

Answer 1

I added EXECUTION_STATE.ES_SYSTEM_REQUIRED, which "Forces the system to be in the working state by resetting the system idle timer," and prevents the system from entering a power saving state. I also changed the API calling convention to use EXECUTION_STATE, wrapped everything in a simple utility class with some documentation.
''' <summary>
''' Simple power manager class that enables applications to inform the system
''' that it is in use, thereby preventing the system from entering the sleeping
''' power state or turning off the display while the application is running.
''' </summary>
Public Class PowerManager
#Region " Private Sub New "
Private Sub New()
'keep compiler from creating default constructor to create utility class
End Sub
#End Region
''' <summary>
''' Enables applications to inform the system that it is in use, thereby preventing the system from entering the sleeping power state or turning off the display while the application is running.
''' </summary>
''' <param name="esFlags">The thread's execution requirements. This parameter can be one or more of the EXECUTION_STATE values.</param>
''' <returns>
''' <para>If the function succeeds, the return value is the previous thread execution state, as a EXECUTION_STATE value.</para>
''' <para>If the function fails, the return value is NULL.</para>
'''</returns>
''' <remarks>
''' <para>This function does not stop the screen saver from executing.</para>
''' <para>http://msdn.microsoft.com/en-us/library/aa373208.aspx</para>
''' </remarks>
Private Declare Function SetThreadExecutionState Lib "kernel32" (ByVal esFlags As EXECUTION_STATE) As EXECUTION_STATE
Public Enum EXECUTION_STATE As Integer
''' <summary>
''' Informs the system that the state being set should remain in effect until the next call that uses ES_CONTINUOUS and one of the other state flags is cleared.
''' </summary>
ES_CONTINUOUS = &H80000000
''' <summary>
''' Forces the display to be on by resetting the display idle timer.
''' </summary>
ES_DISPLAY_REQUIRED = &H2
''' <summary>
''' Forces the system to be in the working state by resetting the system idle timer.
''' </summary>
ES_SYSTEM_REQUIRED = &H1
End Enum
Public Shared Function PowerSaveOff() As EXECUTION_STATE
Return SetThreadExecutionState(EXECUTION_STATE.ES_SYSTEM_REQUIRED Or EXECUTION_STATE.ES_DISPLAY_REQUIRED Or EXECUTION_STATE.ES_CONTINUOUS)
End Function
Public Shared Function PowerSaveOn() As EXECUTION_STATE
Return SetThreadExecutionState(EXECUTION_STATE.ES_CONTINUOUS)
End Function
End Class
Public Class Form1
Private _cancel As Boolean
Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
'set system standby to one minute
_cancel = False
PowerManager.PowerSaveOff()
Do Until _cancel
My.Application.DoEvents()
Loop
PowerManager.PowerSaveOn()
'do not forget to restore your power settings
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
_cancel = True
End Sub
End Class

Answer 2

This works for me:
Private Const SPI_SETSCREENSAVEACTIVE = 17
Private Const SPI_SETSCREENSAVETIMEOUT = 15
Private Const SPIF_SENDWININICHANGE = &H2
Private Const SPIF_UPDATEINIFILE = &H1
Private Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, ByVal lpvParam As Long, ByVal fuWinIni As Long) As Long
Private Sub Form_Load()
Call SystemParametersInfo(SPI_SETSCREENSAVEACTIVE, 0, 0, SPIF_UPDATEINIFILE + SPIF_SENDWININICHANGE)
End Sub
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Call SystemParametersInfo(SPI_SETSCREENSAVEACTIVE, 1, 0, SPIF_UPDATEINIFILE + SPIF_SENDWININICHANGE)
End Sub

Answer 3

Microsoft.Win32.RegistryKey rkScreenSaver =
Microsoft.Win32.Registry.CurrentUser.OpenSubKey(#" Control Panel\Desktop", true );
if ( (string)rkScreenSaver.GetValue( "ScreenSaveActive" ) == "1" )
{
rkScreenSaver.SetValue( "ScreenSaveActive", "0" );
rkScreenSaver.Close( );
}
This should work for you.
Alternatively why not extend the time for the screen saver to 10 minutes?