Both Clients Crash During a Fight

I was playing a Duelist, friend was playing a Templar running a bunch of Minions. While fighting the mob shown in the screen cap we suddenly both noticed the client jump and lag and then we got this error message.

Problem signature:
Problem Event Name: APPCRASH
Application Name: Client.exe
Application Version: 0.0.0.0
Application Timestamp: 510f44b9
Fault Module Name: MSVCR100.dll
Fault Module Version: 10.0.40219.325
Fault Module Timestamp: 4df2be1e
Exception Code: c0000005
Exception Offset: 00002357
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789