>but my application still give 'illegal operation' after a few days. I am running win9x system.
>I am loss on how to solve this issue. Any advise or suggestion
>is greater appreciated.

If you are running VFP6 or VFP7, build an exe with Debug Info (in the project information dialog) on. Then the exception dialog will give the call stack, and line of VFP code which is executing, when the fatal expection occurs. With this information, maybe we can determine what is happening.