Game crashes upon loading or creating a world, and upon joining any kind of multiplayer session.

All forms of firewall and antivirus were 100% disabled at the time this report was generated.

The error is caused when attempting to create a new world, load an existing one from any version, and join any kind of multiplayer session.
The game will reach the "Building terrain" screen, then close, ask me to publish the error, and return to the launcher.
What I've tried and failed at is listed as follows, to save some time:

• Attempted deleting .minecraft and reinstalling from launcher (Did not fix the issue)

• Attempted deleting .minecraft and launcher and installing from updated launcher (Did not fix the issue)

• Attempted full reinstall from .msi file on minecraft website (No success)

• Attempted all of the above with and without windows firewall and avast disabled (Did not fix the issue)

• Attempted downgrading to 1.6.4 (This is the only thing that fixes it so far)

• Attempted swapping out "Microsoft Security Essentials" with "Avast! Free Antivirus" (Did not fix the issue)

• Attempted repeatedly slamming head against wall (Did not fix the issue)

pls help me mojang senpai