i am using a pix 515 . with UR licence. the pix is running 7.22 IOS. the problem is that fter few minutes of working it suddenly stop responding on console hits of enter. it also stops ping reply also. the it reboots automatically. some time after reboot it doesnt work. then i have to reboot 2-3 time to see the green light on front panel. i have erased flash and reinstalled everything. i have replaced the RAM and power supply. nothing help me. can anyone advice what else i can try or any suggestions.