2006 Macbook 13" has just blown its 3rd logic board. Very expensive to replace. Done twice under 3 yr warranty. Not real keen to pay for a new one but just spent $350 on new hard drive and battery.
If it truly is a third logic board, the machine was repaired by a qualified technician, and the machine is still able to be serviced you should ask a genius at an apple store for a replacement.