>when i install my programs on my customers's computers, that use the printer hp 800 series (only), my program causes fatal errors with windows's blue screen. to solve the problem i ask to them to install another hp driver different of the 800 series (hp 600,hp 700,hp 900 or later) and that works.
>how to correct that problem ?

It's not VFP's fault but HP's (wish it was the only problem with HP printers).
Get latest drivers from HP or use the ones that ship with win only. You might also try to use fpreset (documented somewhere on KB) :

DECLARE _fpreset IN msvcrt20.dll

*Any code that deals with printer
=_fpreset()

Cetin