Take a look in your tpl_login_default.php

find this line of code:

Code:
<label class="inputLabel" for="login-email-address"><?php echo ENTRY_EMAIL_ADDRESS; ?></label>
<?php echo zen_draw_input_field('email_address', '', zen_set_field_length(TABLE_CUSTOMERS, 'customers_email_address', '40') . ' id="login-email-address"'); ?>
<br class="clearBoth" />
A check of the source of the login page shows that the highlighted portion is currently set at 431 this is causing the excesive length.

Do the same for:
tpl_modules_create_account.php

Code:
<legend><?php echo TABLE_HEADING_LOGIN_DETAILS; ?></legend>
<label class="inputLabel" for="email-address"><?php echo ENTRY_EMAIL_ADDRESS; ?></label>
<?php echo zen_draw_input_field('email_address', '', zen_set_field_length(TABLE_CUSTOMERS, 'customers_email_address', '40') . ' id="email-address"') . (zen_not_null(ENTRY_EMAIL_ADDRESS_TEXT) ? '<span class="alert">' . ENTRY_EMAIL_ADDRESS_TEXT . '</span>': ''); ?>