vb.net 2008 error log file

Please have a look at:
http://www.codeguru.com/columns/vb/article.php/c6561
http://www.codeproject.com/KB/vb/ErrorsAndEventsExample.aspx

Here's how you can do it:

    Public Sub WriteError(ByVal e As Exception)

        'Set this to the name of your application
        Dim AppName As String = "My application"

        'Set this to the name of the Log (like "Application" log)
        Dim LogName As String = "MyLog"

        Dim log As New EventLog()

        If Not EventLog.SourceExists(AppName) Then _
            EventLog.CreateEventSource(AppName, LogName)

        log.Source = AppName

        Dim msg As String = "The following unhandled exception has occurred in the " & _
            AppName & " application:" & vbCrLf & vbCrLf & _
            e.Message

        'Write the error to the EventLog
        log.WriteEntry(msg, System.Diagnostics.EventLogEntryType.Error)

    End Sub



Write an error like this:

        Dim errMessage As String = "write this error"

        WriteError(New Exception(errMessage))

        MsgBox("done")


You can view the entry in your log:

    Open Windows Administrative Tools | Event Viewer