JS error on login page (IE only) with slow connections

I've noticed that a few other people have experienced similar issues (see posts below), but unfortunately their solutions have not worked for me.

http://www.zen-cart.com/forum/showthread.php?t=109266
http://www.zen-cart.com/forum/showthread.php?t=38017

The following error message is displayed when attempting to view the login.php page.

Line: 4782
Char: 39
Error: 'document.login.email_address' is null or not an object
Code: 0

This error message is only displayed when viewing the site in IE (6/7).

A customer actually informed me about this error. After some initial troubleshooting, I've managed to narrow the cause of this error down to their connection.

They're currently using 56k dial-up to access the site.

I can access the login.php page fine at home and work (both 20mb broadband connections).

To test this theory further, I tweaked my connection settings down to those of a 56k dial-up modem. And, guess what, I too experienced the same JavaScript error with IE7 (and also IE6).

I'm now wondering if this slow connection is causing the page script to timeout.

Does anyone know of a work around for this?

Thanks in advance,

Alex