>As my customer is nervous, he clic too quickly on the mouse and opens sometimes three or four times the same VFP program (.EXE). He is working on an network and this same program is opened by several different people. How prevent that the same person opens it several times on the same station ?

In addition to Sylvain's reply, you might want to look at my article "Create Single Instance Applications" on the FoxPro Advisor site (11/98).