The checkbox I think your're referring to is called 'Run TCStart' in the 'Load at startup' section in General Setup. This is not checked, which means I'm not running TCStart on startup.
So, I don't think this is what caused the issue. And I don't think it would fix the issue if I check the box.
In the 'Add' window I checked 'Don't show again', then clicked 'Close'
It doesn't show up any more, so that solves the issue, I guess.
It's probably, like you say, just an add that hung around from a prior installation.