error reading file : Can't open cdr file

I am not being able to open a .cdr file in Draw. Its about 1.16 gb, I know its big but I didnt realise it has become so big, it has 18 pages now. It was working fine till yesterday. but now when i am trying to open it a pop up comes showing error reading file. I am using x4 in a 32 bit windows 7 with 4 gb ram.
I have tried opening in laptop with 64bit windows 7 4 gb ram, it opened till 80% adn then a different error came which said - invalid object. I need to retrieve the artwork, i have worked on it for more than 3 weeks. The back up file also shows the same. Please help.