Minecraft Servers crash my game when I join them.

I play Minecraft servers all the time. Also, I play on Minecraft.exe all the time, but when I got Minecraft.msi for the first time, things got a bad. When I opened Minecraft.msi, I clicked Multiplayer, and as usual, it would would say Windows Firewall had blocked off the contents of this program. Then I clicked allow, like what you would need to do to access the servers you play on when you download Minecraft.exe and .msi again. When I joined, I was only only on the server for about 0.8 seconds and then it crashed. Then I went to Minecraft.exe and it worked. Then about 3 days later, I saw that Windows Firewall message again on Minecraft.exe this time. I clicked allow, and I joined a server, but it crashed like .msi! This could effect me from joining servers, so I hope someone comes up with an answer.