2007 Buick Rendezvous flashing dash lights

Suspect the generator and the battery. GM's generators, since they redesigned them for the '87 model year, develop huge voltage spikes that can damage the internal diodes and voltage regulator, and interfere with computer sensor signals. The battery is the key component in absorbing and damping those spikes, but as they age and the lead flakes off the plates, they lose their ability to do that. It is real common to go through four to six replacement generators in the life of the vehicle. To reduce the number of repeat generator failures, replace the battery at the same time unless it is less than about two years old.