Lpc2000

Hi
I am using IAR, J-Link and LPC2129. I am running from FLASH with the 
PLL and MAM enabled. The board is the KEIL eval board, but with a 
MAXIM reset device fitted in.

I previously had problems with J-Link connecting to the target with 
the PLL enabled. All these problems disappeared when I updated the 
bootloader code on the LPC2129. Now J-Link connects every time!

BUT,
I now have a much worse problem. 9 out of 10 connects to the target, 
when I press RUN the device appears to run but the interrupts do not 
fire.
1 in 10 connects, everything works fine.

Running the target on its own, by pressing reset, it works every 
time.

What on earth is going on?
If anyone has any suggestions they would be greatfully received. 
Project deadlines are tight and I am on the verge of ditching this 
device and moving to Atmel.

I just hope I am doing something dumb that can be easily fixed.

Many thanks
Simon