Sorry for the lack of info...
The recordset is WADAusers, and I had pasted the wrong string in from my text file where I had changed my field and form element names.
I am opening the Update Record (users) server behavior and in the bindings tab, replacing
<?php echo ((isset($_POST["user_Pword"]))?WA_MD5Encryption($_POST["user_Pword"]):""); ?>
with what should be
<?php echo ((($_POST["user_Pword"] != ""))?WA_MD5Encryption($_POST["user_Pword"]):$row_WADAusers["user_Pword"]); ?>