I have a Dell Optiplex 780. After upgrading to Windows 10 I didn’t see a need to keep avast on it. I went to the avast directory and did an uninstall. When finished it told me to reboot. I did. The boot failed with Windows simply saying it encountered an unrecoverable error. It mentioned the boot device. I’ve tried Microsofts Windows 10 repair utility, but it also fails. I assume the boot sector is somehow locked down. I don’t know what to from here. This was a great computer. I don’t want to just toss it.
How did you uninstall Avast from its program directory? Uninstall is done from Windows Programs and Features,
selecting Avast and then selecting uninstall.