Well, I'm not sure what you mean by small square division. But if you are in FCP 7 or under, when audio tracks go white, in my experience that means your source files have been disconnected from the project. Ctrl + click or rt click on the white file, then in the popup menu choose reconnect media. Then it's just a matter of navigating to your files and reconnecting them. I hope that works for you.
-Grant Gomm
http://www.grantgomm.com