I've had the exact same problem recently and I've used backup files to go back to a point in the project where this did not occur (and with some loss of information of course)

I used the same method you did here with installing the Build 3000, but without the latest hotfix I can't open the 3D window instead, so I'm getting stuck in a catch 22 here...did you find out what the error was?

Has anyone found a solution for this yet,

Had no luck with re-installing the Build 3000 version have logged a case with support but have had nothing yet, becoming quite urgent

I thought I had it...
This happened again as I started working on a backup of my project
As I started to get this message again I disconnected all my hotlinks and libraries. Then I saved the and started to reconnect the libraries and files one after another to see if any of these seemed to be the faulty one

I found that the files in where I used my main project file and which were reconnected to the mainfile were the ones that seemed to cause the problem

But I haven't still found a solution to this.
Unfortunately as of this moment I just saved the project with the files connected and then my computer crashed for some other reason and now when I've restarted it I can't open my main file again because the satellite files where connected when I last saved it

Does anyone have a solution to this!?!?!?!
I need it fast cause Graphisoft's support in Sweden was closed at 1600

AAAAAAAAAAAAAAAAAARRRRRRRGGGGGGGGHHHHH!

And I'm on the same level as Mikasa... It's becoming very urgent!

Still no one with a comment about this problem?

The support has sent my file to the main office in Hungary to see if they can figure out what's happened with it and if they can solve the problem

...until they do...be very careful with using hotlinks in AC13

Just got in the same problem as you, but no backup!
it is a real hell!!
I had saved the module file many times. But no backup file is created along as it is with the .pln file.
Now it is impossible to open a file on which I've been working in two days.
Did u get back ur file fixed from graphisoft?

I have not found a solution yet, but both Oliver and Björns files are sent to the head office. An interesting thing that you Björn told me via phone, is that it worked when you saved it on your local machine, and not on the server.
That may be a direction for us to investigate further..

Håkan

I have also logged the problem with graphisoft I have been told that it might be my NAS but I have been using it for years with older versions of archicad and never had this problem. I have instucted my staff to work on their desktop and copy the files to the NAS at the end of the day however we are still getting the error and it is becoming more frequent.