Well, I’ve been using Avast for about 7 years? And today I reinstalled my computer and wanted to Install Avast Free, Soo I downloaded free version and went custom Install, Selected my language and started the setup, When the setup was at the finish (Finishing setup…) the computer crashed and restarted it self?! Now, I can’t fire up shields nor I can’t reinstall or remove Avast from system! NOTE: This happened before when I reinstalled my system (1year ago)…
how did you reinstall…do you mean using a factory recovery CD or partition and setting it back to factory specc
Nvm… Yesterday after 2hours of nothing, I remembered system restore option, so I restored the computer to earlier time when Avast wasn’t installed. Installed AVG now, Thanks anyways.
PS… But 7 years of using Avast… 
if you restored to a previous time when avast was not installed…but another AV was installed, then this must be uninstalled before you try to install avast
never install multiple AV…
always remove previous used AV before installing a new…
it is recomended to run the vendors removal tool so all leftover files that may conflict are gone…
you find those tools here http://singularlabs.com/uninstallers/security-software/