My 2008 RAV4 recently had a problem with the brakes locking up - all four wheels were affected with no pulling to one side. The problem was similar to those described by "Herman", "Budwaggles", and "Leeboy83". I had the car towed to a dealer's shop and they diagnosed the problem as a defective master cylinder. It was replaced and, after a week of driving the car, the brakes are working fine. This solutions was also described by a Popular Mechanics article which I found in this forum.