I’ve been playing Halo Reach for a good while, but i’ve been running across a lot of problems recently. I’m constantly being falsely reported for the amount of credits i have, yeah it is a lot, but hey, that’s what happens when you leave a guy with his xbox alone all day 
not only that, i’ve been having problems myself with activities, such as team slayer in matchmaking. It seems that every battle has a problem with glitching, the opposing team will be unaffected by any shots and not only that, one of them will have an unusually high rate for kills and near nothing to getting killed themselves. It doesn’t seem to be getting better no matter how many battles i had to deal with it, it’s been getting frustrating enough as it is. I’ve already reported a couple that i believed were hacking, but didn’t seem to make much of a difference. Is there anything that can be done about this?
Nope.
If they’re cheating, they’ll get banned eventually. As unfortunate as it is, individual members of Live really can’t do crap other than hope.
The players can grab the power weapons and camp with them, or they’re just good. Also, lag. It’s MM. No matter how good of a connection you have lag will always be an issue in MM. I’ve been frustrated many times because of it, but I realise that it’s always going to happen.
That’s probably the only downside to MM. Lag, and that’s most likely why you’re shots aren’t connecting.