Images don't appear in Firefox from Define Pages pages

I've looked far and wide and can't seem to find the answer to this problem in Firefox.

My website displays properly with no security warnings both in Chrome and IE. In Firefox it says the security certificate is not valid.

It also does not display images entered with the img tag under Define Pages (namely on my main page). It actually displays the alt text from the img tag as a clickable link (the image is supposed to be clickable).

My site is http://www.gotvapes.com

I have placed the image taking out the alt attribute of the img tag to no avail. Then, it doesn't display anything at all...

I also noticed that some of the PNG images I added show up in sideboxes in Firefox and some don't?

Also in Firefox the images throughout the site that are compressed with the height and width tags display digitall-y (sic) but I don't see this in either Chrome or IE.

EDIT - I just noticed if I make a link http instead of https in firefox, it displays...weird. But I need to make those links https because they show on the secure pages.