TJ,
Unless NI would care to offer dissent, the ONLY way that your diagrams can be removed, is either by selecting that option while saving, or through VI Server. Now, there is a possible way that this could be affecting you. If you are using any software to maintain your source code, such as SCC, or any LabVIEW code that uses VI Server, that could be causing your diagrams to disappear.
I would suggest the following:
Use Source Code Control. I recommend LabVIEW's SCC, Perforce, or (god forbid...) Visual Source Safe. I have experience with VSS and Perforce, and find either acceptable, though you do have to be VERY careful with VSS.
Source Code Control will ensure that two people do not modify the files concurrently. But you also have to be aware
of how LabVIEW marks a VI as changed. When you modify any subVI, ALL callers are marked as modified. Therefore, when you check out code, you have to check out the caller as well. This means that you have to be very careful when working with multiple developers. I strongly recommend that a discipline be adopted to take into consideration this fact about how LabVIEW saves.
Going back to your problem, I would suggest that you make note of anything that may be causing this to happen. Remember, it can ONLY happen through VI server (the most common method) and if a VI is saved with optinos, and the "remove diagram" choice is selected. So, either someone is saving the VI incorrectly, and you don't know it, or some external program, using VI server, is removing the diagrams for you. In either case, using SCC would prevent this disaster, and allow you to easily go back to previous code, as well as determine the most likely source of your problem.
It would also help if you posted a
ll the details about your issue, such as Version of LabVIEW, SCC if any, and any other third party software that may be affecting this.
Good luck