has fixed duration

i finally found the possible reason for mecanim's malfunctioning in my project. "has fixed duration" was unchecked on the transition from idle to move left but not in any of the other transitions i could see. so it was playing move left by default a lot of the time, and it was very much not what i wanted and annoying. can anyone explain to me how "has fixed duration" could do that?

i tried animation by mecanim's settrigger, and that worked initially but somehow became corrupted (couldn't find hash values), then i used animator.play and that worked initially but stopped after i added in some new animations (and i had to do something weird with an empty state to get it working in the first place). now i'm looking at parameters and wondering if i didn't understand the state machine logic correctly. i had it working though ... i am hoping "has fixed duration" was my problem.

edit: aha! the reason it took me so long to find this problem was i had to have the inspector in debug view, for anyone else who has this problem.