I started a new Rhino session, selected my project file from the welcome window and got the question “Do you want to save Untiteled?”. OK, no problem, why not and I pressed yes. The command tell me "File successfully saved as D:…\ProjectFile.3dm. Wow, 1,5GB project file is overwritten with an empty Rhino file.
I’m glad that I tried to open an older incremental saved file only. It’s not really needed. But this is really dangerous. Please fix it so fast as possible.
-Micha
Hi Micha - thanks for the report - was this V6?
Never mind, Micha, I can reproduce this. thanks.
RH-60808 File overwritten with a blank on startup
@Micha , this seems to be hard to reproduce on demand… I did get it to happen the very first time I tried, but I cannot seem to get it to happen again - does it happen every time for you, and if so what is the exact sequence of clicks or inputs?
-Pascal
It’s at V6 and I happen with a project file. Later I tried it with an other file and it happen again.
I tested it now again and it happens too. Quite chaotic:
Micha, can you repeat this is Vray is not enabled?
-Pascal
Yes happened to me too in 2017. Had worked on a project for a week. I going send the file on Friday morning, but to my shock I had managed to overwrite it with an empty file. Must have been in the same way as Micha describes. 
Luckily I managed to rebuild the model very fast that day and send it to the client.
But I’ve almost done it again a couple of times 
Hello - do you also have Vray running?
-Pascal
If I disable V-Ray, than we have an other situation and it works. Rhino doesn’t ask me to save the Untitled document, since nothing has changed. So, I think, the problem isn’t V-Ray. V-Ray is preparing every new opened file, also an empty file. If the user try to close it, than the Rhino code ask to keep the changes and … fails.
Not 100% sure, but likely. I did use vray in that project.
Yeah, something is changing the initial file that Rhino opens - Vray is one possibility, but the problem can be reproduced with a startup command for example. So it is not Vray to blame, it is a Rhino bug, I believe, but Vray can make it show up, it seems. I have also seen this on my system and Vray is not involved, but it only happens very rarely.
-Pascal
Hi @pascal,
I have seen something like this a few times and formed the impression that there is either a timing issue opening the file from the start screen or a process syncing issue - but no evidence, just gut feel.
I don’t have vray.
Jeremy
Happened to me as well, once. But being aware of this I know when to hit cancel. (Also Vray user)
happend to me also i thougt it was my fault fortunatly a backup file existed , indeed anoying and very dangerous, why asking everytime rhino starts for saving this etc etc fix it please
