My website suddenly started giving Error 200 on anything AJAX related!
You've made a change somewhere that is adding &lt;?php to the beginning of all responses.

In "When editing a View" above, you can see this &lt;?php at the beginning of the response text.  Everything after the &lt;?php is valid JSON and so likely the valid response.

I looked at your home page at http://www.spiritmolecule.com and it also has &lt;?php added to the beginning of the HTML source.  This causes the &lt;STYLE&gt; tag to be ignored. &lt;?php&lt;STYLE TYPE="text/css"&gt; gets interpreted as a single unrecognizable tag and so the CSS statement afterwards is displayed as text on the browser.  

HTTP=200 normally means OK (no errors) which makes sense since it was able to respond, just it has the junk &lt;?php in front.  Of course, in a file processed by PHP, &lt;?php means the file is about to start some PHP code instead of HTML/JSON markup.  Did &lt;?php get added to a file NOT processed by PHP (and so &lt;?php is passed thru as response text)?

Only you can know what you did to get &lt;?php added to the beginning of all responses, HTML or JSON.  Do you recall any other files that you changed before going to sleep?  Since the &lt;?php gets added to many (or all?) responses, it is likely in a common file.

Good luck troubleshooting!