Lpc2000

I am having problems recovering after a watchdog reset.
I enable the watchdog, then to test it, I put the cpu
into a loop, toggling a pin connected to a logic probe.
If I set the reset to, say, 3 seconds, then right
on time the toggling stops.  So the watchdog reset
is triggered.

But the processor never comes back to life.  I have to
ground the reset pin to get it to come back.  How does
a watchdog reset differ from a hardware reset?  Are there
some components (PLL?, UART?, TIMER?) that don't get
reset?