MATLAB/Simulink crash on Windows7

Hi,
My MATLAB/Simulink crashes suddenly many times in a day.
I'm very confusing this trouble.
Does anyone know how to resolve that?

libut.dll has a bug??



OS : Windows7 Professional 64bit
CPU: Core-i7-3770K 3.50GHz
RAM: 16GB


--- from here ---
MATLAB 7.9.0.529 (R2009b)
Microsoft Windows Vista Version 6.1 (Build 7601: Service Pack 1)
Java 1.6.0_12-b04 with Sun Microsystems Inc. Java HotSpot(TM) Client VM mixed mode
-------------------------------------------------------------------------------------
MATLAB Version 7.9 (R2009b)
Simulink Version 7.4 (R2009b)
Audio Plugin Generator Toolbox Version 1.0.1914
Communications Blockset Version 4.3 (R2009b)
Communications Toolbox Version 4.4 (R2009b)
Embedded IDE Link Version 4.0 (R2009b)
Filter Design Toolbox Version 4.6 (R2009b)
Fixed-Point Toolbox Version 3.0 (R2009b)
MATLAB Compiler Version 4.11 (R2009b)
Real-Time Workshop Version 7.4 (R2009b)
Real-Time Workshop Embedded Coder Version 5.4 (R2009b)
Signal Processing Blockset Version 6.10 (R2009b)
Signal Processing Toolbox Version 6.12 (R2009b)
Simulink Fixed Point Version 6.2 (R2009b)
Target Support Package Version 4.0 (R2009b)
Wavelet Toolbox Version 4.4.1 (R2009b)
>>


------------------------------------------------------------------------
       Segmentation violation detected at Wed Feb 20 08:27:38 2013
------------------------------------------------------------------------

Configuration:
  MATLAB Version: 7.9.0.529 (R2009b)
  MATLAB License: XXXXXX
  Operating System: Microsoft Windows Vista
  Window System: Version 6.1 (Build 7601: Service Pack 1)
  Processor ID: x86 Family 6 Model 10 Stepping 9, GenuineIntel
  Virtual Machine: Java 1.6.0_12-b04 with Sun Microsystems Inc. Java HotSpot(TM) Client VM mixed mode
  Default Encoding: Shift_JIS

Fault Count: 1



- System
  - Provider
   [ Name] Application Error
  - EventID 1000
   [ Qualifiers] 0
   Level 2
   Task 100
   Keywords 0x80000000000000
  - TimeCreated
   [ SystemTime] 2013-02-19T23:27:39.000000000Z
   EventRecordID 5169
   Channel Application
   Computer
   Security

- EventData
   MATLAB.exe
   1.0.0.1
   4a5fec26
   libut.dll
   1.0.0.1
   4a83571d
   40000015
   00027cc3
   17e0
   01ce0ef85ac55b09
   C:\Program Files (x86)\MATLAB\R2009b\bin\win32\MATLAB.exe
   C:\Program Files (x86)\MATLAB\R2009b\bin\win32\libut.dll
   f2b4336d-7aeb-11e2-ac2a-50465d4ff8e2