Hi TheBigM60, I am Rob, an independent and a 12 time and dual award MVP specializing in Windows troubleshooting and Bluescreen analysis. Please remember as independents we are not responsible for the development of Windows or the computer hardware and drivers. If you will work with me I will be here to help until the issue is resolved.
Windows Defender Offline - also scans for RootKits
https://support.microsoft.com/en-us/help/17466/windows-defender-offline-help-protect-my-pc
Run and review the results of a Windows Defender Offline scan
https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-antivirus/windows-defender-offlinehttps://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-antivirus/windows-defender-offline
Microsoft's Safety Scanner and Windows Defender have some rootkit protection. WD's scan includes scanning for RootKits.
Microsoft's Sysinternals RootKit Revealer - Free
https://docs.microsoft.com/en-us/sysinternals/downloads/rootkit-revealer
Microsoft Doc's - RootKits
https://docs.microsoft.com/en-us/windows/security/threat-protection/intelligence/rootkits-malware
Bleeping Computer - Windows Anti-RootKit
https://www.bleepingcomputer.com/download/windows/anti-rootkit/
Standard Disclaimer: There are links to non-Microsoft websites. The pages appear to be providing accurate, safe information. Watch out for ads on the sites that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the sites before you decide to download and install it.
Please let us know the results and if you need further assistance. Feedback definitely helps us help all.