every time a new launcher is available a warning "virus detected" message appear and stop the download, all I do is allow the "virus file" to be on the computer and run the launcher again, this time the old launcher is updated automatically.
LOL the first time I got this problem I thought the file really had a virus, I tried to clean it with different antivirus and couldn't so I erase all the game and redownload it, I got tired of this problem and tried other servers, other servers has no players or w/e I didnt like it and come back to ultima again with the same problem... so I said "fuck it" and let my pc to get the virus... since then I didnt care if my pc had virus or not, I just keep playing. Since then I just ignore the virus message and allow it on my pc 😜