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,
Thanks again, have a great week,

Jacob Westergaard
Autodesk Premium Support Team
AEC Premium Support Services