If conversion back to bin doesn't work, you can just stick the entity file in txt format into the gameinfo folder and it will still work. If even the txt format file crashes the game, it must be some error you made in the entity file, rather than a conversion error.
You could post the entity file itself here, so we could check wether we can spot any error that slipped by you, or you could convert it to bin and back to txt to see if any "INVALID" tags show up.