i had the same problem, i found it was really just hit or miss on the burn, gone thru 10 disks in 2 days and only 2 work, the other 8 all freeze on the loading screens at various points, but its always consistently the same spot.

u try cleaning it xD
but no reallyy its prob the xbox not able to read the disc and then gets confused or f up and just stops which making it freeze ........bc its a modded disc...not the real legit 1 ...it prob b easier if u just modded the game urself using modding tools and such and then using the real game ....u know usb style

Get a friend to invite you or join session before you're even on the game.

try sign out before you start the game could be a bad burn or worst case a bad iso

not a bad burn or bad iso, i burn all my games, and i download all my games from the same site. And theres only 1 gta 4 eflc thats up right now regardless of whether its peer2peer or private servers and thats MARV3LS, and i have copies of the same iso that worked before i tried modding it. Backup creator ALWAYS has a chance at failing.

its either the iso you have or u have some files got corrupted while you were replaccing the files with the modded ones. so try again and if it does it again then get different mods.