In Response To 'Re: coefficient evaluation'
You wrote "What does that 'Symbol' mean?"
Humm... don't know.
Do a fresh start of Mathematica with the simplest possible notebook that will show this, evaluate the notebook just once from top to bottom, save the notebook and post it. Hopefully that will provide the clue needed to diagnose this.
I'm sorry if that sounds like the generic "empty your browser cache and maybe your problem or you will go away."
Symbol is a Mathematica function. You can look it up in the help system. I'm guessing it is the result of some tiny typographical error that didn't provide a clear error message explaining the problem and how to fix it.