Prova questo
codice:<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Untitled</title> </head> <body> <input type="button" value="OK" id="btnOK"> clicca qui <script language="JavaScript" type="text/javascript"> <!-- document.getElementById("btnOK").disabled = true; //--> </script> </body> </html>