I have a Dell Optiplex 745 with Windows Vista Business, but yesterday I upgrade my SEP from MR4 MP2   to  MR5 (11.0.5002.333), sice then, it had been crashing (blue screen) every five minutes.

I've installed the MR4 MP2 again, and everything is ok.

Checking the minidup file I found the following:
Debugging Details:
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KERNEL_LOG_EXIT_STATUS:  Exit Status 0

KERNEL_LOG_FAILING_PROCESS:  WerFault.exe

PROCESS_OBJECT: 855b4800

DEBUG_FLR_IMAGE_TIMESTAMP:  0

MODULE_NAME: wininit

FAULTING_MODULE: 00000000

PROCESS_NAME:  svchost.exe

BUGCHECK_STR:  0xF4_svchost.exe

CUSTOMER_CRASH_COUNT:  1

DEFAULT_BUCKET_ID:  VISTA_DRIVER_FAULT

CURRENT_IRQL:  0

LAST_CONTROL_TRANSFER:  from 81cda610 to 81b15b0d

STACK_TEXT:
886bdc48 81cda610 000000f4 00000003 855b4800 nt!KeBugCheckEx+0x1e
886bdc6c 81c38f77 81c6e650 855b494c 855b4a28 nt!PspCatchCriticalBreak+0x73
886bdc9c 81c38f1e 855b4800 869f1aa8 c0000005 nt!PspTerminateAllThreads+0x2c
886bdcd0 8c15d449 000000b4 c0000005 85654430 nt!NtTerminateProcess+0x1c1
WARNING: Stack unwind information not available. Following frames may be wrong.
886bdd54 81a92c7a 000000b4 c0000005 000fefe0 SYMEVENT+0x14449
886bdd54 00070000 000000b4 c0000005 000fefe0 nt!KiFastCallEntry+0x12a
0000003b 00000000 00000000 00000000 00000000 0x70000

STACK_COMMAND:  kb

FOLLOWUP_NAME:  MachineOwner

IMAGE_NAME:  wininit.exe

FAILURE_BUCKET_ID:  0xF4_svchost.exe_IMAGE_wininit.exe

BUCKET_ID:  0xF4_svchost.exe_IMAGE_wininit.exe

Followup: MachineOwner
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Apparently there is a problem between svchost.exe  and  wininit.exe

Does anyone have something similar? Or how to fix it?

Regards