Clients dropping off (crashes)

This is the error report from Windows, this hasn't happened to me before the patch.
Playing single client I haven't had any drops just while multiboxing..

Problem Event Name: APPCRASH
Application Name: WoW-64.exe
Application Version: 6.0.2.19033
Application Timestamp: 543d7042
Fault Module Name: ntdll.dll
Fault Module Version: 6.1.7601.18247
Fault Module Timestamp: 521eaf24
Exception Code: c00000fd
Exception Offset: 0000000000050e27
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 6896
Additional Information 2: 6896e1e3fca6f943a3cbd5e4592dc0c1
Additional Information 3: 6659
Additional Information 4: 665952a804520a6ae6b213198b2a7627

System :
Intel i7 4770k
16 gb of ram
256 ssd
Asus Z87-A
Nvidia GTX 780 GeForce 344.11 Driver

None of these are OC'd
Running 5 toons in the "good" setting graphically.