How to do this ....

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1 - download the uninstaller for your version of Kaspersky from their website.
2 - download the installer from avast.com
3 - completely disconnect from the Internet
4 - run the Kaspersky uninstaller
5 - restart your computer & remain disconnected from the Internet
6 - install Avast
7 - if Avast wants to do a boot time scan, allow it to do so
8 - restart your computer & wait for the boot time scan to finish
9 - reconnect to the Internet & update Avast
# Alternately, you can not allow the boot time scan until after you have updated Avast and then select boot time scan from the UI (user interface). It's on the Maintenance tab on the left of the UI.

Let me know if you need more help.

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