We've been using the MPC860TZQ80D4 for many years in one of our product without having any trouble. Now we have two boards with the same problem. When I power up the unit the first time, everything works fine. After 1 minute, if I power down the unit and then power it up the MPC860TZQ80D4 stuck in an infinite loop (time base instruction). If I compare the EXTCLK with the CLKOUT I could see a phase shift (see attachment). Could it be a PLL problem? If I place a 8pF scope probe on the EXTCLK signal the processor starts correctly every single time.