Hi,
You have got the Side-by-Side error in your computer. This is mostly due to the corrupted Visual C++ Package in it.
This is mainly due to failed Windows Updates. So what you need to do first is, to make sure that the Windows Updates are working fine.
You can follow the bellow work around to fix the issue.
1) Download the Visual C++ 2008 redistributable package.
You will get two different packages for 32 bit and 64 bit. So make sure that you download the correct one.
For 32 bit machines.
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=5582 For 64 bit machines
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=2092 2) Click on Save File and save it to the desktop
3) Double click on the downloaded file (vcredist_x86.exe) or (vcredist_x64.exe)
4) Click on Run
5) Follow the on screen instructions to complete the installation process
6) Try to start the Avast, if error message still persist then follow the below steps
7) Click on Start and then click on My Computer

Double click on Local Disk (C, and then click on the Make a new folder in the left pane
9) Copy the file you downloaded into this folder
10)Click on Start and then click on All programs
11)Click on Accessories and then right click on CMD and then click on Run as Administrator
12)In Command prompt, type cd \ms and press Enter
13)Type vcred.msi and press Enter
14)Installer package will install
15)Delete c:\ms folder.
Please update us back. Have a wonderful day.. Good Karma!