I'm using Maple to come up with equations, and then I'm substituting in variable names for functions which I can then output to Matlab.

I haven't had any problems until I ran into partial derivates described by the D[] operator.  For example, if i have a function f described by f(x(t),y(t)) and I differentiate it wrt t, I get 

D[1](f)(x(t),y(t))*(x(t)_dot) + D[2](f)(x(t),y(t))*(y(t)_dot)

I want to make a substitution for D[1](f)(x(t),y(t)) and D[2...

I'm running Maple 12 on my Windows 7 machine, 64-bit.  I never had this issue before when running in on XP (32-bit) for a couple years before I got a new machine.

Basically, whenever I go to Save or Save-As, Maple just closes.  It doesn't freeze or anything, just closes.  This problem is sporadic - sometimes it happens and sometimes it doesn't.  At first it was only doing it with Save and I overcame the problem by just making multiple versions of...