On View Rewrite Results I don't see additional options like Add Read More button when checked "Trim this field to a maximum length"
My guess it is a Jquery incompatabilty. I had the same problem this morning while setting up a new site. After activating views there where no accordions and a faulty overlay. 

So i set the Jquery-version in Jquery-Update Module from 1.8 to 1.5 and everything turned back to normal.

Edit: here's the issue queue on drupal.org: http://drupal.org/node/1869988