Commonly, this is caused by a failure of your code to unload after you
exit.  Make sure that your code is being linked with a standard correct
startup module, and do not use the Exit(n) function to exit your program.
This function will bypass your startup code's cleanup, including its
ReplyMsg() of the WBStartup message (which would signal Workbench to
unload your program from memory).  You should exit via either exit(n)
where n is a valid DOS error code such as RETURN_OK (<dos/dos.h>), or via
final "}" or return.  Assembler programmers using startup code can JMP to
_exit with a long return value on stack, or use the RTS instruction.