I use a Foxpro based system on my job, but the problem is that frecuently appears a message "the instruccion at "0x100017bf" referenced memorya at "....." The memory could not be read. And the system crashes down and this is really annoying because I can't work, does anybody knows hoy to avoid or explain me why is this problem ocurring as I enter more information on my system

How to solve memory problems on foxpro
Arnaud Prost
Dooker
Does the app use any ActiveX
You also need to watch and observe what is being done just before the crash. It is likely something in the code is triggering this event. Unfortunately these types of problems can be a real PIA to debug, because they are often not consistant. Thankfully at least for me, they tend to be rare.
Paulson
http://support.microsoft.com/default.aspx scid=kb;en-us;168277
Since that's the exact address in question I suspect that may be the problem.
VFP5 is almost ten years old, I would suggest it's time for an upgrade.