Same error message occurs with Solidworks 2012 sp 3.0, the latest. File is not actually a Solidworks part so there must be something wrong with the way the file was saved from it's original program.
What CAD system did this come from? I am assuming ProE.
If it is ProE, what version?
I thought it might be an old Cadkey file as they used that extension. However, I just tried opening it in CK99R1 and it would not open it.
It's not a NX file either