This problem is caused by the search skin object. If that is not loaded the password will be 'remembered'. Add this to your skin:

<

script runat="server">
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Request.Url.PathAndQuery.ToLower().IndexOf("ctl=register") > -1 Or _
Request.Url.PathAndQuery.ToLower().IndexOf("ctl=login") > -1 Then
dnnSearch.visible = false
End If
End Sub
</script>

I tried to add that to my skin's Default.aspx, but there was no effect.

Any other things we can try?

My copy of DNN installed on XP allows me to login with "Remember me" checked. Same skin.