I can\'t get to the bottom of this error, because when the debugger is attached, it does not seem to occur.
Collection was modified; enumeration operatio
Actually the problem seems to me that you are removing elements from the list and expecting to continue to read the list as if nothing had happened.
What you really need to do is to start from the end and back to the begining. Even if you remove elements from the list you will be able to continue reading it.