I noticed that "website builder" is tagged for your inquiry.
Are you on GoCentral? Did you add any scripts or code to an HTML widget? If you did, try removing those to see if that resolves the issue. Sometimes malformed code, a missing end bracket or quote can cause that code to conflict with other parts of the background code.
Same thing is happening to us. We select an item to edit it and the page turns white. Tried Firefox (New install), IE and Chrome with cleared cookies. The same thing is happening on all of them.