Opamp and AD835 square-root circuit malfunction - Latches up

I have been using an AD8092 with an AD835 four quadrant amplifier.  The circuit has been used now in product for sometime with no problems but recently i have a latch up problem with the circuit.

The output of the AD835 is in the feedback of the AD8092 op-amp and I am comparing it with an input signal of some pules.  The output of the op-amp is the square-root of the input signal.  The output of the AD835 now latches high and doesn't follow the input signal of the op-amp.

I need some help.

Steve