TC 2.0 oddity - me or it ?

[D Murphy]

I have a program running on a PC which does its job perfectly BUT which 
produces a Null pointer assignment message after it has finished. This
is being caused by something after the last instruction (I tested this
by adding puts("Last"); just before the closing brace of main() and got

Last
Null pointer assignment

and I don't know why this is happening. All the memory allocations and
deallocations work fine, and no pointers get moved around without DOS
being told about it, so does anyone know why this might be happening and
what I can do about it  ?

Murff...