Escualo - the real problem is the project is corrupt - somehow an invalid character has worked its way in. There is something in the project called "player_1_select" which actually contains an unprintable ASCII character like this:
player_1[INVALID CHAR]_select
The invalid character is an unprintable "unit separator" (US) ASCII value 31. I've no idea how it could have gotten in to the project.
What is there in the project called player_1_select and if you rename it does it fix it?