Ok...I've heard back from the host already, and here's what they had to say...
Thank you for the update Derek,
I checked the server logs, however there seem to be no errors related to the issue.
Also, port 80 and 443 are opened by default on all of our shared servers.
Should you have any further questions, do not hesitate to contact us.
Kind regards,
SiteGround Support Team
This has become too stretched out of an issue...I need this to work, no one can register on my site, and new customers cannot purchase items. I know you guys are trying, but I really need resolution to this issue please.