We may be able to help. The MW3 server admin (MW3sa) allows you to kick/ban players who cheat or do other bad things.
Unlike its predecessor, MW3sa comes with a kick button that removes the player only temporarily. It also comes with new improved ban logic that prevents the game from lagging once you ban someone.
Discontinued since version 1.1.0
We'll keep improving MW3sa. With the built-in update check you will be informed when an update is available. Experiencing application crashes? Tell us and we'll start working on it!
As an improvement over our old system, we now ship several versions of the application. As of version 1.1.0, script versions are no longer available. If you want to avoid large downloads: the small packages don't include all the requirements and are therefore more suitable for updates.
Oh, and if you plan to pre-order CoD: Ghosts, get a major discount at G2Play!
Some people may have issues installing the tool. Make sure that you have installed all requirements and use at least Windows 7. Previous versions of Windows may work but are not supported.
The tool will not work if you are behind a proxy. Luckily, the game itself won't work behind a proxy either, so that's not really a problem. Some VPNs are fine.
If the tips above did not help and you are still experiencing difficulties with the tool, please shoot us an email. Include a full description of the problem and maybe some steps to reproduce. Very short or incomplete bug reports (such as "PATHETIC, it doesn't work.") will be ignored.
I'm not only a programmer, I also like helping people with issues they're having (which may explain why I wrote MW2sa and MW3sa). I've written a guide that should help you solve some network issues which may help you get MW3sa working better. For example, with a strict NAT you aren't going to be able to host which will definitely be a problem.