FP6116 Asynchronous Step-Down Regulator

[Jane]

I have a Linux embeded board that  uses
FP6116 Asynchronous Step-Down Regulator
a datasheet  is here
http://www.micro-bridge.com/data/Feeling-tech/FP6116.pdf

In this design , that Asynchronous Step-Down Regulator  should supply 1,2V for  CPU  on this board.
It worked for some time but now it stopped.
So, I measured voltage and that Asynchronous Step-Down Regulator  still supply 1.2V, yet CPU does not start.
But when I use a different source of 1.2V, the CPU starts.
So, I am rather confused.
I can measure the same voltages, and more or less the same spikes( using oscilloscope), yet different results.

Can anyone suggest any solution to that problem?
Thanks