Unable to add new listings

Hi, I'm having a serious problem where no new listings can be added to my site. I think this has been going on for a while but have just now confirmed the problem.

Once you reach Step 3 of the posting process you will receive a blank page when you hit Next. (included pics)

Users also can not access the My Profile page from the menu, clicking on it will result in a blank page.

If I go into the admin console and try to change any Profile Details for a user clicking Save will result in a blank page.

I also can not add any new listing from the admin console, I again get a blank page when I try to create them.

I've also noticed that the blank pages use a different browser tab icon then the normal site. It uses an older version that was removed a while ago.

What can I do to fix this problem? I need an answer ASAP as I have customers that need postings.

EDIT: The website is http://www.talkingads.ca. If you need access to anything just let me know and I'll message you the info.

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EDIT 2: Problem solved. It was the QR Code plugin. I re-installed the plugin and everything is working fine now. Not sure what happened with it but at least it's fixed.