Can't Checkout - Login Page Won't Load...

Hi Y'all...

Everything has been going smoothly thus far, until about five minutes ago when I encountered a pretty significant problem: you can't checkout. For some reason, the "Checkout" links and the "Login" links don't pull up the correct pages. I'm not sure what the heck is going on.

Does anyone have a second to take a look at the site to see if they have any clue where the error may be? At this point, I'm lost. :)

If you have a second and don't mind, I can PM you the site address. The business owner would flip if they saw their site listed.

After Thought: Does anyone know if using a service such as PreviewDNS to edit a site that hasn't launched yet can interfere with Sessions, therefore causing the login page to not load?