Little boxes with hex code in it. How to fix?

Some webpages now show buttons only as boxes with hex code in it. What happened? How to fix this?

Added (1). It was fine some time before, then I update java and let java uninstall old versions.
It happens on many webpages now, other webpages have different wrong depictions.

Added (2). All these icons are buttons, working just fine, when clicking or hovering on it.
These pages use javascript, but I can't find how they get the image.

Added (3). I'm just the user of these sites.
The example is from
http://www.techsupportalert.com/best-free-iphone-apps.htm
No idea, how they look in real.

Added (4). I also startet my browsers (IE and firefox) in no-add-on mode.same result for the buttons.

Added (5). Thanks, Spac3nerd brought sparked the right direction.

Your question starts with
"Little boxes with hex code in it."

I want it to say
"Small rectangles with hexadecimal codes in them."

How to fix?

Some things are just not fixable.

Note: I'm assuming you are NOT the author of the webpage you showed.

However, IF you are the author, then you'd have to show us how you created those boxes.

Note: You can't change someone else's webpage, but you could make a copy of their webpage and change the local copy. Your local copy would not reflect subsequent changes they might make in the future. And, while your local copy *might* display correctly, it might not have the functionality you might want.

Overall, it's not really clear what you are asking. Do those hex codes have *any* meaning to you?

I suppose that the image resources that are supposed to be loaded are not. Either they are no longer available, or something on your computer or network blocks them from being downloaded.

If you know how to use the browser dev tools, look at the DOM tree and see what those icons are, and where the images for them are coming from.
Also look at the network tab and see if the downloads are failing. If those are supposed to be images, each one should have a GET request, my guess is that they are failing for some reason.

The last possibility is that your browser is not compatible with the resources used by the website.

The site you linked to uses FontAwesome to display small logos and images: http://fortawesome.github.io/Font-Awesome/
Each rectangle is a unicode character that is supposed to be displayed using a specific custom font full of symbols.

If for some reason the font failed to load, the browser will fall back on a default font, which doesn't contain glyphs at the unicode positions stated in the code. In that case the browser will display said rectangle with the Unicode # inside.

The website is pulling the font from here: http://www.bootstrapcdn.com/
If that fails, you will get the boxes.

The reason could be your DNS settings. Also try powercycling your router once in a while, they often run months on end.

It has nothing to do with Java, JavaScript or Images.

I think I found a solution.
Checkmark "Allow pages to use their own fonts". In firefox37 it is in Tools-Options-content-Font&Colors-Advanc…

Yes. It is due to a setting in your firefox. I have not found similar settings in Chrome and IE, however I believe there's a plugin normally used for people who do not use English fonts which may cause such problems as well. The fact is that while Bootstraps use of FontAwesome is very cool, in the long run I don't believe it is going to be something which we will want to continue in the future. Media such as images, video, gifs and sound are just that, media. Fonts should remain able to be localized and should be only for text. Separation of concerns. Sorry FontAwesome. You should not be used.