xbox 360 lag and crash. (crash interfere with singleplayer data and it is really freaking annoying)

When I bought the game and played it at home it did not lag. After a couple of days it started lagging. When I lag while running it put me back where I started running and I have to run straight again.

The game randomly crashes in loading screen constantly. I remeber this happen too on Battlefield 3. Please fix this. I mean I dealt with this in Battlefield 3 and now your making me do this again. Also when the game crashes it delete the single player save data. This also happened in Battlefield 3. I was more than half way finish with singleplayer and it was very boring. Now I will never play the single player campaign again. 

Other side effects from crashing include your sever filter being reset (all the tick marks are untick)

Sometime you get a complete reset and the game is introduce to you again and your settings will also be reset

please get this straighen out!!!! 

And I still have not unlock my grenades.. Bullcrap.. I see people throwing impact on me and I have to eat their metal shrapnel