You need to take it to a dealer and have the computer reflashed.
The allowable amount of mistakes in one line of code is 10. GM's quality control before their bankruptcy was less then stellar and they built a lot of junk. Not to be outdone, their updates are sometimes no better then the origional programs. My dad bought a new '07 Impala 2 years ago and when he took it in for service, the service manager told him that he had updated his computer as per the recall notice. Well my dad informed the service manager that he did not want his car updated. The service manager got smart with my dad and said , well we did it anyways.
The problem was that my dad drove almost 100 miles one way to buy this car and he drove another 100 miles one way to have it serviced and you guessed it - 2 days later when the computer crashed, he had to drive another 200 miles to go back and have the Power Train Control Module replaced.
My dad is 73 years old and does not put more then 3,000 miles total on his vehicle in a years time. So let's just say that he was deeply upset.
Rewind a few years before all this and I knew several people who had the same problem as you people were having and every one of them was due to the computer turning on something and then not turning it off. It wasn't the ABS - it had more to do with a shift motor and other things on the transmission and transfer case. When the PTCM fed too much power into those items, once the vehicle got 40,000 - 60,000 miles on it - guess what?
They died and the owners had to spend even more money to repair and replace everything that went bad.
