Put the summary of the bug you're having here

What I expected to happen was...:
Me to be able to log onto my favorite server called McBestCraft. Name isn't important, but it is running 1.7.10

What actually happened was...:
After I clicked the 'Join' button, I got the logging in screen, and then I crashed

Steps to Reproduce:
1. Not entirely sure, but play 14w30c
2. Switch to a different profile set up for 1.7.10
3. Launch Minecraft
4. Try to join a 1.7.10 server