Locked out of Project - cannot open .cpr file.

I was testing some additional vst plugin voices (Analog Lab 2) in a project and got a message to update Analog Lab 2.
I saved the project, closed Cubase 7.5 and updated Analog Lab2 from the Arturia Software Centre. When I went to open my project again Cubase started to load from the .cpr and then hung halfway through after loading a couple of vst plugins and I got an error message saying
“A serious problem has occurred. Please try to save your project under another name and the restart Cubase 7.5 .exe”
I can’t do that because Cubase is completely hung at that point…i.e. I cant get into the project to save it. So I can only Ctrl/Alt/Delete to get out of it. (I waited three hours at one point to see if it would resolve)
Other older projects are still ok, but that one (nearly six months’ work!!!) is inaccessible. A crashdump file was created and I can see the .cpr and all the .BAK files in the project folder. But I can’t open the project itself.
Sadly our great support guy in Singapore is no longer working for Yamaha here and there is no software support.
Any feedback appreciated.