Gavagai Explorer is not designed to handle concurrent use by several people of a single project.
Doing so will result in problems such as corrupt projects, inconsistent results, and unpredictable behaviour.
To avoid such problems we encourage and constrain use of an account to a singe user at a time. This is for the protection of the integrity of customers' projects and to minimize potential support issues. The solution is to have 1 account per user. If you need to share project data across several accounts please see this post.