Message is: "Unable to launch C:/Users/Public/Installed Games/EverQuest00/eqgame.exe - 225: Operation did not complete successfully because the file contains a virus or potentially unwanted software." Google failed me, or perhaps I failed google. Anyone?
That message is thrown by Windows Defender not Everquest. I would proceed as if my computer really had a virus and run a WDO (Windows Defender Offline) scan.
So, I restarted about five times with both accounts, ran validate assets twice, somewhere around the third launch and before the second validation I threw out (deleted) eqgame.exe, then finally posted here and Discord in frustration and sadness, tried launcher again, restarted again - and now it seems fine. Well, either fine or Eastern European hackers used it to hack my system, validated I had nothing worth stealing and moved on. But probably it's the "I'm fine" thing.