if you used the trainer, and your health meter drops to zero with infinite health you won't be able to use that save game. i found this out when i exited the game for a bit and when i tried to reload i kept dieing as soon as it loaded even if i started the trainer and turned infinite health on.
EDIT: seems to be a random occurence after a relaunched again. you just have to remember to turn the trainer on at the menu and turn the infinite health on......
[Edited by tyler274, 1/26/2011 12:30:16 PM]
let me just put here that this is NOT going to 'break' your game. the glitch is purely graphical.
at any rate, i looked at the trainer(s) and updated it. pwizard will post shortly-
best,
Cal