Unleashed 1.1.4 crash to desktop

[verid]

On Unleashed 1.1.4, I'm crashing to desktop without any Minecraft log, seemingly randomly. It can occur after 15 minutes of play or after 150 minutes of play and even when not doing anything in the world (it has happened while I was alt-tabbed once). This is in SMP on the client - the server does not experience these random crashes.

All I get is a Java error log in the launcher directory.

Spoiler

#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000007fefaed6220, pid=5092, tid=2044
#
# JRE version: 7.0_25-b17
# Java VM: Java HotSpot(TM) 64-Bit Server VM (23.25-b01 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C [OpenAL64.dll+0x6220] alSourcei+0x144
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# If you would like to submit a bug report, please visit:
# http://bugreport.sun.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

What I've tried:
- Both with and without Optifine
- Uninstalled 32 bit Java and reinstalled 64 bit Java
- Checked Nvidia drivers up to date

So far no luck. Anybody have any suggestions?