Hi vineethmohan,
Do you mean the image attached?
I have no trouble viewing this, so I would assume that the installation has been messed up.
Can you try a repair of Avast?
Start-->control panel-->add/remove programs -->avast antivirus --> click remove --> scroll down and click repair
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As a workaround, if this doesn't work, you could disable it in the avast4.ini file:
Navigate to: C:\Program Files\Alwil Software\Avast4\DATA\avast4.ini
You will need to find this:
[Simple]
ShowHelpCheckList=1
Change it to 1, like above and close notepad. You will be prompted to save, and also prompted by the self-defense module if you did this. Say yes to both and then try to open the simple user interface.
-Scott-
EDIT:Image....