I just had a frightening experience, I hope that this post will prevent anyone else encountering the same problem.
Tip:
When you are setting up game_text messages, never ever, EVER put the text to be displayed in quotation marks.
Doing so will stop the VMF loading into hammer and give you a horrible scary error message.
For the last hour I'd thought I'd lost an entire weeks mapping! It's scary as hell.
Thankfully, you can fix the problem by taking the quotation marks out of the VMF with notepad or similar, and then the file will load into hammer again.
But hopefully you'll never have to do that now.
Well, I gotta get back to mapping......
(Day 13 is about 70% complete)