Yes, I’m sure it’s a plugin conflict.
But how I fix it if I downgrade to 1.2.5. I thought you might be interested to know.
My other plugins list:
Advanced Custom Sort
Advanced Excerpt
Akismet
AVH Extended Categories Widgets
Easy FancyBox
Executable PHP widget
Hide Title
Highlight Search Terms
Linkify Authors
List Authors
MediaElement.js - HTML5 Audio and Video
Reveal IDs
Simple Taxonomy
TDO Tags Fixes
TinyMCE Advanced
TinyMCE Excerpt
Top Level Categories
Ultimate tag cloud widget
Widget Logic
WP Super Cache