So one day I got that "Cheat Detected" message, I was banned. So I installed MW2 Liberation, and I was able to bypass it, but it says there are 0 players online. When I hit "Find Game", it never joins. Before I was banned, it still said 0 people online, but I was able to connect to server after 3-5 minutes of waiting.
You can only host matched and play private matches using MW2 Libaration.
You can go into a public lobby, press F4 to force host and then press F5 to start the game. Then you can hope that someone joins.
I recommend starting with FFA in the TDM playlist and then changing gamemode when you lobby is full as the enemies does not forfeit.