Hello Alec,
What browser are you using? It sounds like you may have your browser settings set to delete cookies when you exit the browser. I recommend checking your browser settings. If this setting is not selected, try deleting your cookies, closing the browser, entering the zip code, logging in, then close the browser, and try to access the site. This time it should not ask you to enter in your zip code. If you continue to have an issue, it may be related to your security software not accepting the cookie.
What browser are you using? It sounds like you may have your browser settings set to delete cookies when you exit the browser. I recommend checking your browser settings. If this setting is not selected, try deleting your cookies, closing the browser, entering the zip code, logging in, then close the browser, and try to access the site. This time it should not ask you to enter in your zip code. If you continue to have an issue, it may be related to your security software not accepting the cookie.