Checkout issue with IE

Hi there,

I've found other threads with similar problems to this, but unfortunately no solution.

When a user tries to checkout in IE, they are taken back to to the "Please create or select an address" screen, despite the fact that an address has already been entered an chosen.

Steps to reproduce:
1. Select a product from the table here: www.telephone-english.com/index.php/prices-formula
2. Fill in the registration form.
3. Click the activation link in the email.
4. Attempt to make a payment via credit card or Paypal.

Result: User is returned to "Please create or select an address" page every time they try to pay. This doesn't happen in Google Chrome or Firefox.

Any help would be greatly appreciated.

Thanks.

Not knowing how to fix it or really what that error message means, I removed all javascript and mentions of it in index.php (just to see if that was it) It disabled javascript elements such as the slider, but the same problem still occured.

Can you recommend a quick fix?

OK, thanks.
Could you please tell me how to were able to see the javascript error in the first place?
Many thanks again!