Can't link images on Squarespace posts

When I try to add links to images, the box to do so shows up and then the page freezes. I first had this problem a couple of weeks ago. It lasted three days and then resolved itself. Now it's back, and Squarespace support insists it must be the result of custom code I added. I wouldn't know custom code if it bit me on the nose, so I certainly didn't add anything. Has anybody experienced this problem before?

I just posted an image in my blog on my 7.1 sandbox site. I  linked it to a Facebook page. It worked fine. Does this happen with any link or a specific one? Are you using 7.1 or a 7.0 template? If it is 7.0 which one?