Having two resident anti-virus scanners installed is one too many and not recommended as rather than provide twice the protection it can cause conflicts that could leave you more vulnerable. Not to mention avast free shouldn’t be running on a business system, even if it were the only AV.

These conflicts can present themselves in many ways, detection of the others processes is just one. Since you don’t say what the file name and location of this hidden rootkit/s are or what detected them (presumably avast) ?

If avast, you don’t state what scan you did regular on-demand scan (Quick, Full or Custom and settings) or if it was the anti-rootkit scan 8 minutes after boot ?

If this is a work system and you are forced to run McAfee, you aren’t left with much choice but to uninstall avast.

I can’t help with the OTL log as it isn’t something that I’m familiar with.