I've noticed that when Comments Evolved for WordPress is installed with The Events Calendar Plugin from Modern Tribe,it breaks the admin css for event setting, and event settings on single events pages.
I've been able to recreate the issue in a live and development settings with only these two plugins and other plugins, both with premium and basic (2012) themes running.
Same situations. Activation of Comments evolved breaks Events Calendar.
It turns form elements and meta boxes wild. Drop down are fully dropped down and always visible. Border around all form elements.
I really liked comments evolved, but Ive got a ton invested in the events. Too much to change calendar. let me know if you need more info on this or find antyhing else out.