CoD 4 frustration

Evert time I back out of a game type online, all of the progress I just made, including levels, achievements and XP are erased and I revert back to the level I was when I turned on my console. Every time a message pops up saying "unable to join gametype" and I have to go back to the main screen and then go back into XBOX live, thats when all of my recent stats are erased. It is as if I hadn't even played.

Any help would be greatly appreciated.