Installus.xyz is a malicious pop-up presented as a fake alert claiming that you need to install some Flash SD App. The reality is that there is no need for you at all to do that. If you mistakenly proceed with the misleading guidelines mentioned by the Installus.xyz pop-ups, your browser will be hijacked. There will be a special extension installed, plus you will also notice that there are some unwanted changes to take place with your default search engine. Please follow this guide below explaining how to fix your system effectively.