Crashes on Multiplayer/ .msi launcher won't download

Whenever i open Minecraft from the minecraft.exe launcher, everything works fine. I can play single player without any crashes, manage everything in the options list fine, and as well as open the realms section. But, for some reason every time i hit the multiplayer tab, minecraft unexpectedly crashes. Honestly i don't know when this started to happen.

Every time I try to download the .msi launcher (because i figured it would help my previous problem above) I get an error message saying "this user is a temporary file." I don't know what this means but it is annoying! then the .msi launcher setup file says "the process stop prematurely. click finish to close the tab." I just want to play minecraft on multiplayer bur i can't. PLEASE FIX THESE BUGS MOJANG!!!!!!