PIX running on FO license will reboot after sometime. I can't remember the exact time.
To make it run like primary, you need to upgrade the license from FO to UR, see this link for Platform License Upgrade http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_data_sheet09186a00800b0d85.html
Contact your vendor.
thank you for your answer but I cannot conment make for upgrade the licence from FO to UR. moreover I do not arrive has to reach the link that you gave me
Search for this product number "PIX-525-SW-FO-UR=" its the product number of Platform License Upgrade from FO to UR.
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