Launcher Bug.

I do not know why but when I try to load 17w43a and 1743b from my launcher it loads correctly then the launcher vanishes but the game crashes and kicks me back to the launcher, which sucks cause I would like to try out the new snapshots, does this happen to anybody else?
Basically I can download the stuff needed and sometimes the bar goes funny and crashes or it boots up and crashes. I got screenshots of a before and after to prove it this time, and I think I mis categorized it last time sorrry.