Overactive ABS?

I posted this "over there", but since I'm never sure who's banned and who's not, I wanted to tap in to the knowledge base over here.

I'm Looking for some help with a problem on my '95 Caprice Wagon:

I noticed this for the first time on the way to work this morning. I was coming to a moderate stop, roads were wet. All the sudden, the ABS took over, and the car was not stopping! It was acting as if I was on a solid sheet of ice. If I were in fact on a solid sheet of ice, it would have been doing the right thing... but as it turns out I wasn't, and ended up having to hit the burm to avoid the back end of a Suburban.

After the incident, the ABS light was on. I had full brakes at that point, but with out the ABS function. I verified this by inducing some skids. Every time it acted like regular old non-ABS brakes.

Now when I re-start the car, the ABS light is off. All is well until I stop too quick, calling on the ABS. Same thing happens - the ABS comes on way too strong, and it takes the car forever to stop (again as if I were on ice). At some point during the stop, the light will come on and the ABS will stop functioning.

Any ideas? I've never had trouble with the ABS function before on any of these cars so I'm not sure where to start. This car in particular has been in my fleet forever. Rotors are at least 7 years old, the brake pads are somewhat new (maybe 10,000 miles), rear brakes are about the same age with new drums. Car has stock 2.56 gears and auto trans. Bone stock. It had been sitting all winter and this was the first weekend that I had it out. It was stored in a heated, humidity-controlled garage.

Thanks in advance for any help!

Guesses:
1. Either the brain is bad, or..
2. One of the three wheel speed sensors is giving a zero or highly intermittent signal to the computer. I'd check the continuity and resistance of the circuits at the brain and verify that they are connected and non-intermittent.

Maybe a spider set up housekeeping in your reluctor vanes. I have the same problem with both of my wagons. Once the antilocks come on, the car just keeps on a rollin'. Once, I ended up completely in an intersection. I have no idea about the parameters for the activation. I have contemplated unplugging them.

the sensors on the wheels tend to rust. it is a magnetic pickup. Pull the rotor and clean both the cogs and pickup and see what happens........ good time to check the bearings too......