I HAVE GOT OFFICIAL REPLY ON MY EMAIL-
here is exact message->
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The avast! UI got hooked with your explorer.exe process you would need to reinstall the avast!.

  1. Uninstall the version of avast! that’s currently installed on your
    computer using our uninstall utility, that can be downloaded from this
    page:

http://files.avast.com/iavs9x/avastclear.exe

  1. Use it in safe mode of Windows - in this mode you don’t need to
    disable the avast’s self-defense module. Here you can learn how to
    start Windows in safe mode:

http://www.pchell.com/support/safemode.shtml

  1. After using that tool, restart your computer.

  2. Ensure there’s no “alwil software” nor “avast software” folder in
    C\Program Files and if it is, delete it

  3. Download the latest version of avast! from this page:

http://files.avast.com/iavs9x/avast_free_antivirus_setup.exe

http://files.avast.com/iavs9x/avast_pro_antivirus_setup.exe

http://files.avast.com/iavs9x/avast_internet_security_setup.exe

http://files.avast.com/iavs9x/avast_premier_antivirus_setup.exe

  1. Install it with default values, i.e. do NOT change anything during
    the installation process, and everything should be OK again. Finally,
    insert your license file (if you’re using the paid version) or
    register the program (if you’re using the free version). Your license
    file can be sent again upon filling up this form:

http://www.avast.com/resend-license-paid.php

If you need further assistance, don’t hesitate to contact me again.

Best Regards
Albert Fiala
avast! Technical Support Specialist

Ticket Details
Ticket ID: ITD-666-58575
Department: Technical Support (Consumer AV)
Type: Communication
Status: On Hold
Priority: High

Support Center: https://support.avast.com/index.php?
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but this solution seems not to be working!!