What should I do after finding a rootkit on my PC?

You're not alone; many have had issues with malware that masquerades as legitimate processes like Google Updater. I've seen cases where these "click fix" infections embed themselves into the system. While I wouldn’t say this is your specific case, it’s good to do some digging on where it might have come from. Just remember, if you're not comfortable sifting through the code, it's best to let an expert handle the cleaning.

First off, you need to find out how that rootkit got onto your system in the first place. Think about any suspicious downloads or installations you've done lately. Just removing it with antivirus software might not be enough, as rootkits can be tricky. Honestly, I recommend doing a complete reinstall of Windows. And while you're at it, it's a good idea to reset passwords for all important accounts you’ve accessed recently.

Which antivirus did you use for the cleanup? If it was Avast, be cautious; it's not always the most effective. A fresh Windows install is usually the safest route to eliminate any leftover threats. Moreover, ensure you're using some sort of real-time protection. Even Windows Defender may be preferable over irregular scans. Also, remember that sometimes malware can get into your computer just through malicious browser extensions without needing any downloads.