multiple users not allowed on excel workspace......

I have a document that is currrently saved as an .xlw as i believed that is how to save a document for multiple users to access at the same time. things work great for the first hour or so then suddenly it comes up as locked for editing for all except one user (user varies). i have looked at other threads and it says 2 users cannot save at the same time. however this is not the problem as i have confirmed that no users are saving and it is still locked. If anyone can help i would appreciate it. Thanks