in my case the trial software write an encrypt line burrow deep into window sub directory, nothing a total brand new hard drive won't fix. And of course you can always reformat your spare hard drive as long as you please.
if game available try reinstall the game then use add/remove to delete it, you may also want to check start up folder and delete any reference to this game, there was a utility to remove .msi file but I don't remember where I get it.