In fairly hot weather, usually after car sets at a show or something like that, I will apply the brakes, and the front brakes will not release. If I break open a bleeder or line, it releases and may not due it again for 3 months or so. Does anyone have any ideas??  

next time it happens break the fitting loose at the master cyl. and work your way to the wheels where ever there release will be the next thing up from that fitting I've seen the master cyl. filled right to the top make this happen to the fluid expands without anyplace to go as it makes enough press in the sys. to hold the brakes up let me know what you find  

You might check to insure that you have enough "free play" on the MC pushrod with the brakes released.