Have you updated Windows Defender? Have you performed a system scan with it? If not, please do so (and let us know if it finds infections).

Please rerun Driver Verifier according to these instructions: Driver Verifier Settings
Make sure to let the system crash several times - then check in C:\Windows\Minidump to see if memory dumps have been created.

While waiting for a reply, please start with these free diagnostics: Hardware Diagnostics

Analysis:
The following is for informational purposes only.
Code:
**************************Wed Jul 31 12:47:57.273 2013 (UTC - 4:00)**************************
Loading Dump File [C:\Users\John\SysnativeBSODApps\073113-36296-01.dmp]
Windows 8 Kernel Version 9200 MP (4 procs) Free x86 compatible
Built by: 9200.16628.x86fre.win8_gdr.130531-1504
System Uptime:0 days 3:16:34.345
Probably caused by :csrss.exe
BugCheck EF, {a5e9f800, 0, 0, 0}
BugCheck Info: CRITICAL_PROCESS_DIED (ef)
Arguments: 
Arg1: a5e9f800, Process object or thread object
Arg2: 00000000, If this is 0, a process died. If this is 1, a thread died.
Arg3: 00000000
Arg4: 00000000
PROCESS_NAME:  csrss.exe
BUGCHECK_STR:  0xEF_c0000005
FAILURE_BUCKET_ID: 0xEF_c0000005_IMAGE_csrss.exe
CPUID:        "Intel(R) Core(TM) i5-4430 CPU @ 3.00GHz"
MaxSpeed:     3000
CurrentSpeed: 2993
  BIOS Version                  F2
  BIOS Release Date             04/17/2013
  Manufacturer                  Gigabyte Technology Co., Ltd.
  Product Name                  Z87-HD3
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3rd Party Drivers:
The following is for information purposes only.
Any drivers in red should be updated or removed from your system. And should have been discussed in the body of my post.
Code:
**************************Wed Jul 31 12:47:57.273 2013 (UTC - 4:00)**************************
MpKsl8617c29d.sys   Fri Sep 16 17:34:23 2011 (4E73C0DF)
RtNdPt630.sys       Thu Sep 13 07:38:24 2012 (5051C5B0)
Rt630x86.sys        Thu Oct 25 05:15:15 2012 (50890323)
intelppm.sys        Mon Nov  5 22:52:05 2012 (50988965)
HECI.sys            Mon Dec 17 14:32:20 2012 (50CF7344)
nvhda32v.sys        Mon Feb 25 00:27:13 2013 (512AF631)
RTKVHDA.sys         Tue Feb 26 07:37:31 2013 (512CAC8B)
iaStorA.sys         Mon Apr 22 15:37:37 2013 (51759181)
dump_iaStorA.sys    Mon Apr 22 15:37:37 2013 (51759181)
nvlddmkm.sys        Fri Jun 21 05:03:10 2013 (51C416CE)
MpKsl8617c29d.sys - this driver hasn't been added to the DRT as of this run. Please search Google/Bing for the driver if additional information is needed.
RtNdPt630.sys - this driver hasn't been added to the DRT as of this run. Please search Google/Bing for the driver if additional information is needed.
http://www.carrona.org/drivers/driver.php?id=Rt630x86.sys
http://www.carrona.org/drivers/driver.php?id=intelppm.sys
http://www.carrona.org/drivers/driver.php?id=HECI.sys
http://www.carrona.org/drivers/driver.php?id=nvhda32v.sys
http://www.carrona.org/drivers/driver.php?id=RTKVHDA.sys
http://www.carrona.org/drivers/driver.php?id=iaStorA.sys
http://www.carrona.org/drivers/driver.php?id=dump_iaStorA.sys
http://www.carrona.org/drivers/driver.php?id=nvlddmkm.sys