Get the username of a process

Have you tried using System.Environment.UserName for comparison? Or is your problem more complicated than that? Otherwise you might have to use some native calls...please post back if that's the situation...

See:

SystemInformation.UserName

Gets the user name for the current thread (the name of the user currently logged on to the operating system).

[Visual Basic]
Public Shared ReadOnly Property UserName As String

[C#]
public static string UserName {get;}

[C++]
public: __property static String* get_UserName();

[JScript]
public static function get UserName() : String;

Property Value
The name of the user currently logged on to the operating system.

No, I want to know the username of all processes of my application.

Suppose the user "Administrator" starts an instance of Application.exe.  Then, another user (username "Blah") logs onto the same machine with Remote Desktop Connection and starts another instance of Application.exe.

When "Blah" open Application.exe, I want this instance to know that the first instance is used by "Administrator".  If Blah opens Application.exe twice, I want the second instance to end right away (I already do that), but I don't want to end Blah's instance if the first one is used by another user.

Is it clear ?  (I'm not that good in English, sorry)

This shows a VBScript to do that, but you can do the same thing with WMI from within your VB program.

http://www.microsoft.com/technet/scriptcenter/guide/sas_prc_fywf.mspx

Thanks a lot for your help.  

newood put me on the track and I finally went this way :

            Dim query As New SelectQuery("Win32_Process")
            ' Initialize an object searcher with this query
            Dim searcher As New ManagementObjectSearcher(query)

            ' Get the resulting collection and loop through it
            Dim mo As ManagementObject
            Dim NbThisUser As Integer = 0
            For Each mo In searcher.Get()
                Dim arOwner(2) As String

                If CStr(mo("Name")).ToLower = Diagnostics.Process.GetCurrentProcess.ProcessName.ToLower & ".exe" Then
                    mo.InvokeMethod("GetOwner", arOwner)
                    If SystemInformation.UserName.ToLower = arOwner(0).ToLower And SystemInformation.UserDomainName.ToLower = arOwner(1).ToLower Then
                        NbThisUser += 1
                        If NbThisUser > 1 Then
                            End
                        End If
                    End If
                End If
            Next