Hi
I had a similar
problem to this on my girlfriends' Peugeot 206cc over xmas. I pulled the ABS fuse to stop the ABS kicking in as it was kicking in for no reason under braking & reducing the efficiency of the braking rather than improving it. Pulling the ABS fuse will disable the ABS and T/C but at least it will make the car driveable so you can get it fixed. with the pug it turned out to be the reluctor ring had completely snapped off and disappeared! the reluctor ring is located behind the disc & hub area, it is a splined ring (looks kind of like a cog/gear), and should rotate with the drive shaft. It lines up with the ABS sensor in the hub, this is how the sensor detects the rotation/acceleration/decelleration of the wheel.
I'm not quite sure if it can be easily viewed from underneath the
ibiza or if you will need to remove the wheels in order to get a good look, may as well check the ABS sensors for any damage, broken wires etc while you're in there, also check your tyre presures and your fuses to make sure there's not something obvious.
the pug needs a whole new driveshaft to replace the reluctor ring as it is built-in but I should think on most cars the reluctor ring can be bought as an individual part. Hope this is of some
help, I spent half my christmas holiday under her car figuring it out!