Hi,
Thank you for taking your time to write this in the forum,
There are various reasons for file corruption, it's a general thing with all kinds of files. However, there are some areas that are more common than others, such as:
- Read/write failure to the storage media.
- Program crashes (especially when writing data to the RVT model).
- An add-in that modifies elements in ways not possible or desired through the normal UI.
- Untested operations or series of operations (e.g. cancelling a synchronize, or using the Undo command after synchronizing).
Throughout the lifespan of Revit 2015 we have 14 updates where each one of them contributes to a functioning product. So if you haven't already, I would check that every single user is running the latest version and this applies to all our products - the Autodesk Desktop App will notify you every time there's a new update - it will be the same for whatever release you may be using.
Note: Updating will not correct already corrupt files.
As to you specific file, if you want I would be more than happy to go through the file and correct whatever might cause conflict.
I will just need you to confirm and I'll send you a link to a folder where you can upload your file.
In any case let me know how you would like to proceed, and if you consider my responds sufficient enough, please mark it as a solution.
Thanks again, have a great week,

Jacob Westergaard
Autodesk Premium Support Team
AEC Premium Support Services