Matlab Student R2013a compatibility with Windows 8.1?

I've installed R2013a student version, and EEGLAB 13_1_1b. When I try to process data, it fails in an eeglab function, but tracing the source of the error back up the stack to the previous function, I examined nargin to see what it was set to. Each time I evaluate it, it CHANGES. Even though the program has stopped running:

EDU>> nargin

ans =

      22

EDU>> nargin

ans =

     206339072

EDU>> nargin

ans =

     206339072

This makes me very worried that Matlab is not working properly on Windows 8.1. I've tried running as administrator and in Windows 7 compatiblity mode. It always fails in the same place, and trying to examine nargin gives random values

EDU>> nargin

ans =

      12867670

EDU>> nargin

ans =

     153470976

EDU>> nargin

ans =

     153470976

Is this an expected behaviour of nargin after the code has ceased to execute?

The code in question looks like this:

function [EEG, com] = pop_select( EEG, varargin);

com = '';
if nargin < 1
    help pop_select;
    return;
end;