Well, you may stay skeptic with this kind of reports but that's what I'm gonna do: report what I have seen in the behaviour of the lop.om sponsoort installation.
As I use Firefox for my daily surfing needs, I didn't care about the sponsor and I installed it, to see what problems it could give and what were the changes to Internet Explorer, as I didn't care much about it.
Well, a couple of months after (well, yesterday) I decided to remove the sponsor. I just uninstalled Messenger Plus! and installed it again refusing the sponsor. I opened Internet Explorer and everything was right again, no bars, no popUps, no messed-up error pages, fine.
But the surprise came today, when I started the computer. The bar was there again along with the popups and all that bullshit.
So (thinking of corrupted files) I re-installed (without uninstalling first) with the sponsor program. Then inmediately uninstalled MP!. I even rebooted at that point the machine, following the recomendations of the uninstallers. Then checked MSIE, fine without adbar. Then installed MP! *without* the sponsor and the bar surprisingly re-appeared.
I have done all steps exactly this way and it is not possible that I missed the checkbox, whatsoever.
I will try now to uninstall before re-installing with sponsor, but I'm afraid that won't help much.
Hope there is a rational (ie, neither mystical nor spiritual) explanation for this.
Edit: forgot to say that Internet Explorer had no window open. (although a process of it seems to be impossible to finish, maybe due to Messenger 7.0)