The latest version of avast is 6.0.1125, so I would suggest doing a clean reinstall of avast.

  • Download the latest version of avast, 6.0.1125 (see below) and save it to your HDD, somewhere you can find it again (if you didn’t save your last download). Use that when you reinstall.

  • Download the avast! Uninstall Utility, aswClear.exe find it here and save it to your HDD (it has uninstall tools for both 5.x and 6.0.x).

    1. Now uninstall avast! (using add remove programs, if you can’t do that start from the next step), reboot.- 2. run the avast! Uninstall Utility from safe mode, first for 5.x if previously installed and then for 6.0, once complete reboot into normal mode.- 3. install the latest version, reboot.

Free AV: - http://files.avast.com/iavs5x/setup_av_free.exe
Pro AV: - http://files.avast.com/iavs5x/setup_av_pro.exe
AIS: - http://files.avast.com/iavs5x/setup_ais.exe