For labcoatman. Do you use NextGen Gallery ? in that case, nextgen setting thumbnail javascript effect is probably causing the problem.
See http://wordpress.org/support/topic/412822?replies=1#post-1560832 for solution.
Thanks…That did the trick. My thumbnail effect was set for thickbox.
Changing to shutter worked.
I had same problems as labcoatman. Upgrade Mandigo to 1.42 no solution for me. I had to de-activate NextGen Gallery Plugin to have sidebar problem solved. I believe some CSS from NextGen Gallery screws up Mandigo’s sidebar handling, but I am definitely a newby on CSS so dare not look for solution myself.