Best thing everyone playing this game could do is to backup the game save data as you progress. I play this game a lot and it has frozen several times, in both, single player and multiplayer, deleting every progress you have made in single player. I also know what you mean, the mods in multiplayer resetting, but this only happens with the most wanted cars and can be fixed playing the most wanted races again, though if the game crashes afterwards you will have to do it again making it a sucking never ending cycle. So copy your save game data to a flash drive and if it crashes delete the corrupted data and copy your back up file. Hope this helps.
