How to lock Clipboard?

Question

Please look at the snippet ----------------------------------- 1 RichTextBox rtf = new RichTextBox(); 2 Bitmap img = new Bitmap(@"c:\myImage.bmp)) 3 Clipboard.SetDataObject(img); 4 rtf.Paste(); ------------------------------------ when the program control passes line number 3 and if I copy some other text/image in the Clipboard using "Control + C", the earlier image 'img' gets vanished. Is there any way to lock the clipboard for other operations till I paste the image 'img' in RichTextBox? Please Guide