Hi,

Try to follow the bellow steps

  1. Download the Visual C++ 2008 redistributable package
  2. Click on Save File and save it to the desktop
  3. Double click on the downloaded file (vcredist_x86.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
    8 ) Double click on Local Disk (C:), and then click on the Make a new folder in the left pane
  8. 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.

Try to open avast! GUI. If the issue still persists please let us know.