Brake Problem with 2000 GLX

["Da Doctah" <docluni@phc.net>]

I was wondering if anyone else has seen something like this or has an idea
as to the cause:

I've noticed this a few times since I bought this car. I'll accelerate with
my foot almost to the floor (before the click), after the automatic switches
to 2nd or 3rd, I'll get a loud beep and a warning message telling me to stop
and flashing the brake light at me. A few seconds after letting off the gas,
the light and stop message will go away. This seems to be a brake fluid
problem. I've checked my levels and they seem fine. I took it to the
dealership and had them flush and refill my fluid. I still see the problem.
Am I expecting too much for this car to perform to it's limits without
giving me serious error messages? Perhaps my brake fluid sensor is faulty?