ABS and traction control problem

hi there

ive got a strange issue with my traction control and abs system.

on first start the yellow light for both systems is on, but if you turn the car if and back on, the lights disappear and the systems work perfect.

when I took the car for diagnostics they said that the fault reads that the Abs computer needs replacing. that's it!

has anyone seen or better still found a fix for this, and what are the root causes?