Game crashes on Ubuntu 12.10

On ubuntu, since upgrading from 1.3 to 1.4, the game crashes after approx 5 minutes. This is not an overheating issue. I have the game set to 1024MB memory, have updated LWJGL, and am using OpenJDK. The entire computer locks up and refuses to accept input.

Also reported at Gaming.SE: http://gaming.stackexchange.com/questions/90495/minecraft-crashing-ubuntu-12-10