It's quite probable the the VFP IDE has some parts of itself like the resource file, intellisense manager et.al. that have consumed some amount of buffer that you can't possibly flush.
>Somebody have a answer to this result ?
>
>? SYS(1104)
>
>
>CLEAR ALL, close all projects not change the result of SYS(1104).
>
>I can do a command to force SYS(1104) to return 0 ?