Google Drive keeps breaking Calibre's paths due to its parentheses fussiness.
I've written a Python script here
https://github.com/mendhak/calibre-gdrive-fix
which fixes the paths that Google Drive breaks. It should work as long as you have Python 2.5+.
I've only tested this on Ubuntu 14.04 with Python 2.7. If this works/doesn't work for you in other OSes please leave feedback or fixes.
See the README on github for info and instructions.
I am aware of
this thread, however that is a .NET solution and I don't have .NET/Windows. I'm using a similar script as part of my initial machine setup script for automation.