How to detect Windows 2000 workstation is locked/unlocked?

Posted on 2008-10-01
Last Modified: 2013-11-07
Using: VB.NET 2008 with Framework 2.0
Platform: WIndows 2000 SP4

Unable to find an entry point named 'WTSRegisterSessionNotification' in DLL 'wtsapi32.dll'.

I need to detect when the user has locked or unlocked their workstation in order to start/stop certain procedures from being called. I have gotten the following code to work on machines running Windows XP or above, but receive the error described if the OS is Windows 2000. Unfortunately, there are still a lot of users that run Windows 2000.

This doesn't throw an error in Windows 2000, but it also doesn't work. :(

Dim SessionSwitchHandler As New SessionSwitchEventHandler(AddressOf PhoneQueueMonitor_SessionSwitch)

Can someone please show me (sample code, please) how to do this on Windows 2000 using VB.NET 2005/2008?
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Me.Load
' Works in Windows XP and above but not Windows 2000
AddHandler SystemEvents.SessionSwitch, AddressOf SampleForm1_SessionSwitch
End Sub
Private Sub SampleForm1_SessionSwitch(ByVal sender As System.Object, ByVal e As SessionSwitchEventArgs)
        If e.Reason = SessionSwitchReason.SessionLock Then
            ' Computer locked
            Console.WriteLine("Workstation locked at: " & Now)
        ElseIf e.Reason = SessionSwitchReason.SessionUnlock Then
            ' Computer unlocked
            Console.WriteLine("Workstation unlocked at: " & Now)
        End If
    End Sub

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Question by:blitzzy
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LVL 11

Expert Comment

ID: 22621502
WTSRegisterSessionNotification is only supported by XP and Vista.

Have you tried to build it on a win2k machine ?

Author Comment

ID: 22623642
Hi melmers,

Yes, I have tried to run the program on a Windows 2000 machine. That's when I get that error on load. If WTSRegisterSessionNotification is not supported on Windows 2000, then how can I get the same functionality?
LVL 11

Accepted Solution

melmers earned 500 total points
ID: 22623695
a quick goolge have bring me this site where is an example

But i don't know if it works with Win2k because i have no win2k pc
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Author Comment

ID: 22624071
I've seen this example before. It's so complicated! I tested it but it doesn't seem to work on 2000.
LVL 11

Expert Comment

ID: 22643962
are there any errors ?

Author Comment

ID: 22649780
I've played around with and made modifications tothe code in the link that you sent me and finally got it to work.

Author Closing Comment

ID: 31502148
Provided useful information and code sample that required modification. Thanks for the help.

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