Trouble with different customers seeing different pages

[KMatt]

Users that were created prior to January see one set of site pages (specifically during check-out) and customers created after January 1st see a different set of check-out pages. All products are set to ship for free so the site skips the Shipping page for checkout. Originally the default is a 3 step checkout process. With free shipping Zen skips shipping making it a 2 step process. I have edited the text to say Step 1 of 2 and Step 2 of 3. These new users see the old 3 step process.

Any ideas what might be causing this?

On further investigation it seems to be users created from Internet Explorer versus users created using FireFox. Any thoughts on what might be causing this difference? I access the site through the same URL from each browser.