Sorry, I don't understand what you mean. Can you show me the output code (put list on perhaps) or show the code and the memory in the debugger?
I've found the bug and surprise surprise it was in my code - sorry
I was using interrupts and when the code wasn't optimised the timings were okay, once optimised there were conflicting and registers were getting screwed up (despite me thinking I'd preserved them). The 4 bytes I saw was the colour codes from the interrupt to change the screen colours.
I was going along the lines of memory leak because 1) I'd forgotten about interrupts and 2) I've been trying sjasmplus recently and that has a problem with them.
PS - Can I have a copy of a later version than 2.0 Alpha 18 if you've got one please? Also, is there any possibility that you'll release a command line version of the assembler so it can be used with PSPad etc?