Our Indesign CS6 files are not auto locking anymore. They used to. Now.. either you can not see the
lock when someone has a file open... or it lets you open a file someone else is edition. Causing
major productions issues. Only change we made was moving files to a different NAS server.
I've moved your question to the InDesign forum, where you're more likely to find a helpful answer.
Similar post the other day... I believe changing the network protocol to SMB fixed it. Be sure you have the 8.0.2 patch for ID installed as well.