Help! How do I fix an "illegal or misplaced operator" error in Adobe Illustrator?

I'm working in a very large file in Adobe Illustrator, around 3GB in size.  I've been able to save successfully, close and reopen - UNTIL - I moved the file over to an external drive.  Upon doing so, whenever I try to re-open the file I get the following error:

Adobe Illustrator Error Message:

I'm able to see a preview of all of my art boards with the associated work when I go to File/Open..and click on the file in question:

Adobe Illustrator thumbnail preview of my corrupted file:

However, when I click open, most of the art boards are blank.

I've searched up and down the Adobe forums and other places on the internet for a solution.  I tried three suggestions, all with no success: 

1.  I've tried the trick where you save the document as an .EPS and try to insert it into a new Illustrator document. 

2.  I've tried "placing" each page into a new document inside of Illustrator, Photoshop and InDesign. 

3.  I've tried changing my Illustrator preferences  /enableContentRecovery from 0 to 1.

     I downloaded a text editor that's able to read very large files.  I tried searching for the error inside of the code, but was unable to find that string of text from the
      error message, I searched for "1_iu" the last characters in the error message.

Details:

Computer: 64 bit, PC.

AI Version: CS6

System: Windows 8.1 Pro.

Problem: .AI file saved successfully, and I was able to reopen it on my desktop.  I had to move the file over to a different drive, and when I tried to open again received the illegal or misplaced operator error.

None of the solutions I'm finding have fixed my problem.  I'd like to understand why the error occurred so I don't repeat the mistake, and I'd like to find out a solution to recover my file.  I don't understand how if Illustrator can show me a preview of all of the pages...why the actual document comes in as blank pages?  Please help!