Shoutbox

You need to uncheck 2 checkboxes to prevent Plus! from installing any (additional) sponsor material. This is the current sponsor dialog (5.10.0.750):

Unchecking one box does not uncheck the other.

I think the reason why suddenly there is so much feedback on the sponsor material is because the sponsor dialog changed recently. This is the sponsor dialog from a slightly older version (5.01.0.706):

It looks largely the same, but there is a big difference in functionality. In older versions unchecking 'Install the Messenger Plus! toolbar' would also automatically uncheck the two (sub)options below it. In the new installer 'default search' and 'homepage' are no longer automatically unchecked when you uncheck the 'toolbar' option.


Also, AFAIK there is only an uninstaller for the toolbar in IE, which is labeled 'Messenger Plus! Community Smartbar'. Uninstalling the toolbar does not restore the homepage, search provider, searching from URL bar. Neither does it uninstall the toolbar from other browsers. Each of these modifications have to be restored manually by going trough the browser settings.

Personally I find this far from ideal (to put it nicely). Requests for a proper sponsor uninstaller have been made multiple times but was never created.