MC 15 mpl_exception

I'm using MC15 m010.  When I run the long program in the attached sheet I wind up with an mpl_exception error message. 

None of my co-workers have ever run into an mpl_exception.

This same sheet runs fine using an excel sheet which only utilizes variables with the "1" subscript.  The sheet was expanded to incorporate an additional "2" subscript set of data.  The excel sheet is pretty small, 120KB or so

Is this a memory error? 

Any ideas?

Thanks.