Solidworks errors

[R3P0]

Need any advice on how to recover 12 hours of CAD work. THE only time I don't make backup copy and this happens. First the error:

An attempt was made to access an unnamed file past its end.

What happened is the school that we work in had Solidworks 2009-2010 and I took an assembly that was created on those machines. Then I inserted this assembly into my chassis that was drawn in Solidworks 2011 ( this years version). I saved the 2011 file and closed out. When I went back to load this into e-drawings or Solidworks I get that message.

It apparently allowed me to save the drawing with the 2009 assembly in it, only to truncate itself as if it's a 2009 drawing and not a 2011 drawing.

Any way I can go and edit the file by hand with something to remove the whole assembly that is from 2009 and get my file back?

Of course Solidworks can provide no support cause they gave us the software for free.

/rant WHY does Solidwork change their files EVERY year so we can't use other versions. What a mess. I am really discouraged now with this product. What a waste. /rant

ugh. *facepalms to sharp corner of desk*