You're welcome! I'm glad it is working for you. I know there is nothing worse than the feeling you've lost a lot of work. And sometimes redoing work a second time feels more painful than originally doing it.
Even if you don't use a formal source control system, it is a good idea to make backup copies of your project regulary. Do it when LabVIEW is closed (sometimes moving or copying things while a project is open increases the risk you cross-link files among your different copies.) Move it to a directory where it is unlikely for your project to search to find subVI's when it is looking for them. Zipping up your whole folder as a .zip file is a good suggestion as LabVIEW isn't going to look in there. And moving it to another drive such as a network drive so something like a hard drive crash won't wipe you out.
It's possible the mixed signal graph was the problem as well. I noticed it had data stored in it. I didn't see how much. But it might have increased the amount of memory used by the VI that you might have run out of memory when you opened it causing LV to crash. Hard to say. Fortunately the VI was saveable.
