File Custody Software

When working with teams, what software do you use to keep track of who has custody of the current version so that one person doesn't overwrite the changes of another user?

We store our files on a network (and as you may know, Articulate recommends against using Storyline over the network and I have seen this is for good cause) and so we copy local, edit and then save back to the network.

We have run into some problems with this and would like to know if anyone knows of any solution which will allow someone to "check-out" the latest version, make changes and then "check-in" the latest.