I have a bunch of background events.

All of them call a log:

private void log(string text, params object[] values)
{
    if (editLog.InvokeRequired)
    {
        editLog.BeginInvoke(
            (MethodInvoker)delegate
            {
                this.log(text, values);
            });
    }
    else
    {
        text = string.Format(text, values) + Environment.NewLine;

        lock (editLog)
        {
            editLog.AppendText(text);
            editLog.SelectionStart = editLog.TextLength;
            editLog.ScrollToCaret();               
        }
    }
}

Sometimes I get this, but other times not:

System.AccessViolationException was unhandled
  Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
  Source=System.Windows.Forms
  StackTrace:
       at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam)
       at System.Windows.Forms.NativeWindow.DefWndProc(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.RichTextBox.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, Int32 msg, Int32 wParam, Object& editOle)
       at System.Windows.Forms.TextBoxBase.ScrollToCaret()
       at Program1.frmMain.log(String text, Object[] values) in 
       ...
       ...
       ...

P.D: Not always stop at this line, randomly will be one of the three times editLog methods/properties are used. Not always a exception is throw. Sometimes look like the thing freeze. But not the main UI, just the flow of messages (ie: log look like is never called again)

The app is a single form, with background process. I can't see what I doing wrong with this...