Lpc2000

Hi, I wonder if anyone has seen this before.

While developing the firmware for my LPC2138-featured board, I noticed 
that the bootloader is not always invoked after a reset with P0.14 low. 
Even when the bootloader is not invoked, the device still responds to 
reset.

I tested with the Philips bootloader utility, which, measured at the 
reset and P0.14 pins, gives me:

1) At T+0, P0.14 goes down from 3.3V to 0V sharply.
2) At T+0, Reset starts going down from 3.3V to 0V in an RC-type curve 
of 750µS.
3) At T+750µS both Reset and P0.14 are now 0V.
4) At T+500 mS reset starts going up, having been effectively low for 
499mS. The rising curve is also RC-type and takes about 2 mS to reach 
85%.
5) At T+840 mS, P0.14 goes up sharply. This is 338 mS *after* reset 
went high.

By the spec, these figures should be large enough to trigger the 
bootloader, and it does, except when I've been playing around with my 
firmware for a while (several cycles of compile+flash programming, 
tests, an occasional crash, watchdog triggered, etc.). When the 
bootloader stops responding, the only way to regain the bootloader is 
by removing power.
Any ideas?

Guille