The driver that appears to be the problem is the mfewfpk.sys:

 kd> !analyze -v
*******************************************************************************
*                                                                             *
*                        Bugcheck Analysis                                    *
*                                                                             *
*******************************************************************************

WORKER_THREAD_RETURNED_AT_BAD_IRQL (e1)
Arguments:
Arg1: 83833535, address of worker routine (do ln on this to find guilty driver)
Arg2: 00000002, IRQL returned at (should have been 0, but isn't).
Arg3: 862d7198, workitem parameter
Arg4: 862d7198, workitem address

kd> dps  862d7198
862d7198  00000000
862d719c  890ef008
862d71a0  83833535 nt!IopProcessWorkItem
862d71a4  862d7198
862d71a8  8adaacc0Unable to load image \SystemRoot\system32\drivers\mfewfpk.sys, Win32 error 0n2
*** WARNING: Unable to verify timestamp for mfewfpk.sys
*** ERROR: Module load completed but symbols could not be loaded for mfewfpk.sys
 mfewfpk+0xbcc0

The mfewfpk.sys is a McAfee firewall driver and the problem you are experiencing is similar to that reported in the following thread:

http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/system-bsods-several-times-a-day-report-says/f03e8ad6-35ac-4b53-8223-bc4bc1200a10

As in that thread there also appears to be Microsoft Security Essentials installed on your system so I would suggest to uninstall McAfee and Microsoft Security Essentials and then install a fresh copy of either Microsoft Security Essentials or McAfee but not both.

Also since McAfee and/or Microsoft Security Essentials may not have been working properly consider running a scan with the following two applications just to see if they pick anything up:

TDSSKiller:

http://support.kaspersky.com/faq/?qid=208283363

Malwarebytes Antimalware (free version) - do a "Quick Scan":

http://www.malwarebytes.org/products/malwarebytes_free