Problem: Tried to install Sophos onto a laptop and I got the following error:
“Cancelled installation because existing third-party security software could not be uninstalled…”
I also tried installing by unchecking the “uninstall third party software” option but got a similar error.
Solution: Turns out that AVG 2013 was installed on the system. Even though I ran AVG’s uninstall program, there were still elements of the program in the registry and the file system. I did a search on the whole C: drive for AVG and deleted everything I found. I then went into regedit and deleted every reference to AVG 2013. Rebooted the computer and the installation of Sophos was successful.
How I was able to find every instance of AVG in the registry was by going into regedit and within the menu, click on “Edit” and “Find” or do a ctrl-F. Type AVG in the “find what” section and click on the button that says “Find Next.” Every time it finds an AVG reference, delete it. Be sure to double check before you delete. There are some registry entries that will have avg in it but not be part of the program. I then ran CCleaner just to make sure.
*NOTE: as always, be sure to make a backup of your registry before you delete anything.